Human Emissions Fuel Extreme Weather, Flooding That Harm Humans and the Environment

7/31/2019 Human Emissions Fuel Extreme Weather, Flooding That Harm Humans and the Environment

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Two seminal Nature papers join growing body

of evidence that human emissions fuel

extreme weather, flooding that harm humans

and the environment

ByJoe Rommon Feb 16, 2011 at 5:12 pm

Here we show that human-induced increases in greenhouse gases

have contributed to the observed intensification of heavy

precipitation events found over approximately two-thirds ofdata-covered parts of Northern Hemisphere land areas. These

results are based on a comparison of observed and multi-model

simulated changes in extreme precipitation over the latter half of the

twentieth century analysed with an optimal fingerprinting technique.

Changes in extreme precipitation projected by models, and thus the

impacts of future changes in extreme precipitation, may be

underestimated because models seem to underestimate the

observed increase in heavy precipitation with warmingThats from the first of two seminal studies in Nature, Human

contribution to more-intense precipitation extremes (subs. reqd). The

second looked at Anthropogenic greenhouse gas contribution to flood

risk in England and Wales in autumn 2000 (subs. reqd):

Occurring during the wettest autumn in England and Wales since

records began in 1766 these floods damaged nearly 10,000 properties

across that region, disrupted services severely, and caused insuredlosses estimated at 1.3billion.

Here we present a multi-step, physically based probabilistic event

attribution framework showing thatit is very likely that global

anthropogenic greenhouse gas emissions substantially
http://thinkprogress.org/climate/2011/02/16/207545/two-nature-paper-join-growing-body-of-evidence-that-human-emissions-fuel-extreme-weather-flooding-that-harm-humans-and-the-environment/http://thinkprogress.org/climate/2011/02/16/207545/two-nature-paper-join-growing-body-of-evidence-that-human-emissions-fuel-extreme-weather-flooding-that-harm-humans-and-the-environment/http://thinkprogress.org/climate/2011/02/16/207545/two-nature-paper-join-growing-body-of-evidence-that-human-emissions-fuel-extreme-weather-flooding-that-harm-humans-and-the-environment/http://thinkprogress.org/climate/2011/02/16/207545/two-nature-paper-join-growing-body-of-evidence-that-human-emissions-fuel-extreme-weather-flooding-that-harm-humans-and-the-environment/http://thinkprogress.org/climate/2011/02/16/207545/two-nature-paper-join-growing-body-of-evidence-that-human-emissions-fuel-extreme-weather-flooding-that-harm-humans-and-the-environment/http://thinkprogress.org/climate/2011/02/16/207545/two-nature-paper-join-growing-body-of-evidence-that-human-emissions-fuel-extreme-weather-flooding-that-harm-humans-and-the-environment/http://thinkprogress.org/author/joe/http://thinkprogress.org/author/joe/http://thinkprogress.org/author/joe/http://www.nature.com/nature/journal/v470/n7334/full/nature09763.htmlhttp://www.nature.com/nature/journal/v470/n7334/full/nature09763.htmlhttp://www.nature.com/nature/journal/v470/n7334/full/nature09763.htmlhttp://www.nature.com/nature/journal/v470/n7334/full/nature09762.htmlhttp://www.nature.com/nature/journal/v470/n7334/full/nature09762.htmlhttp://www.nature.com/nature/journal/v470/n7334/full/nature09762.htmlhttp://www.nature.com/nature/journal/v470/n7334/full/nature09762.htmlhttp://www.nature.com/nature/journal/v470/n7334/full/nature09762.htmlhttp://www.nature.com/nature/journal/v470/n7334/full/nature09763.htmlhttp://www.nature.com/nature/journal/v470/n7334/full/nature09763.htmlhttp://thinkprogress.org/author/joe/http://thinkprogress.org/climate/2011/02/16/207545/two-nature-paper-join-growing-body-of-evidence-that-human-emissions-fuel-extreme-weather-flooding-that-harm-humans-and-the-environment/http://thinkprogress.org/climate/2011/02/16/207545/two-nature-paper-join-growing-body-of-evidence-that-human-emissions-fuel-extreme-weather-flooding-that-harm-humans-and-the-environment/http://thinkprogress.org/climate/2011/02/16/207545/two-nature-paper-join-growing-body-of-evidence-that-human-emissions-fuel-extreme-weather-flooding-that-harm-humans-and-the-environment/http://thinkprogress.org/climate/2011/02/16/207545/two-nature-paper-join-growing-body-of-evidence-that-human-emissions-fuel-extreme-weather-flooding-that-harm-humans-and-the-environment/


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increased the risk of flood occurrence in England and Wales in

autumn 2000.

in nine out of ten cases our model results indicate that

twentieth-century anthropogenic greenhouse gas emissions

increased the risk of floods occurring in England and Wales in

autumn 2000 by more than 20%, and in two out of three cases by

more than 90%.

Scientists have predicted for decades that human-caused global

warming would increased extreme weather events that cause severe

harm to humans, property, and the environment. These two studies are

but the latest in a growing body of scientific literature demonstrating

that these predictions are coming true now.

They should help lay to rest the myth that human-caused global

warming will contribute to grievous harm only in some far-off future.

They also strongly support the view that the human-induced increases

in greenhouse gases have contributed to the devastating extreme events

that hit Australia and other parts of the world in the past several

months, helping to drive up food prices (seehow extreme weather,

climate change drive record food prices).

The NYThas a great headline on this story, Research Links Heavy

Rains and Snow to Humans. It is all heavy precipitation that humans

are intensifying.

Of course, many of our top climate scientists have been documenting

and explaining these types of conclusions for a while. Ill list a bunch of

the papers below. Kevin Trenberth, head of NCARs Climate Analysis

Section, has a new paper out, Changes in precipitation with climate

change that is well worth reading. So I asked him for a comment on

these two studies. He told me:

These studies are very reasonable, and the main mechanism is well

understood: it relates to the increased moisture in the atmosphere with

higher temperatures and warmer oceans. However, the studies may
http://climateprogress.org/2011/01/20/lester-brown-extreme-weather-climate-change-record-food-prices/http://climateprogress.org/2011/01/20/lester-brown-extreme-weather-climate-change-record-food-prices/http://climateprogress.org/2011/01/20/lester-brown-extreme-weather-climate-change-record-food-prices/http://www.nytimes.com/2011/02/17/science/earth/17extreme.html?_r=1&partner=rss&emc=rss&pagewanted=printhttp://www.nytimes.com/2011/02/17/science/earth/17extreme.html?_r=1&partner=rss&emc=rss&pagewanted=printhttp://www.nytimes.com/2011/02/17/science/earth/17extreme.html?_r=1&partner=rss&emc=rss&pagewanted=printhttp://www.cgd.ucar.edu/cas/Trenberth/trenberth.papers/ClimateChangeWaterCycle-rev.pdfhttp://www.cgd.ucar.edu/cas/Trenberth/trenberth.papers/ClimateChangeWaterCycle-rev.pdfhttp://www.cgd.ucar.edu/cas/Trenberth/trenberth.papers/ClimateChangeWaterCycle-rev.pdfhttp://www.cgd.ucar.edu/cas/Trenberth/trenberth.papers/ClimateChangeWaterCycle-rev.pdfhttp://www.cgd.ucar.edu/cas/Trenberth/trenberth.papers/ClimateChangeWaterCycle-rev.pdfhttp://www.nytimes.com/2011/02/17/science/earth/17extreme.html?_r=1&partner=rss&emc=rss&pagewanted=printhttp://www.nytimes.com/2011/02/17/science/earth/17extreme.html?_r=1&partner=rss&emc=rss&pagewanted=printhttp://climateprogress.org/2011/01/20/lester-brown-extreme-weather-climate-change-record-food-prices/http://climateprogress.org/2011/01/20/lester-brown-extreme-weather-climate-change-record-food-prices/


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well be conservative as the tools available (the climate models), do not

simulate precipitation and all of its characteristics (intensity, frequency

etc) as well as we would like to see.

As the first study makes clear, future changes in extreme precipitation

are likely to be worse than the models suggest.

In anextended interviewlast year on the subject, Trenberth explained:

I find it systematically tends to get underplayed and it often gets

underplayed by my fellow scientists. Because one of the opening

statements, which Im sure youve probably heard is Well you

cant attribute a single event to climate change. But there is a

systematic influence on all of these weather events now-a-daysbecause of the fact that there is this extra water vapor lurking

around in the atmosphere than there used to be say 30 years

ago. Its about a 4% extra amount, it invigorates the storms, it

provides plenty of moisture for these stormsand its unfortunate

that the public is not associating these with the fact that this is one

manifestation of climate change. And the prospects are that these kinds

of things will only get bigger and worse in the future.

Lets hope these new studies helped put an end to the underplaying ofthe link between human caused emissions and the extreme weather

events we are experiencing now.

The Washington Post has a goodpieceon the two studies, Greenhouse

gases led to increase in deluges, researchers say, with more quotes:

Human influence on the climate system has the effect of intensifying

precipitation extremes, said Francis Zwiers, a climate researcher at

Environment Canada in Toronto and lead researcher on the first study.

Zwiers and his team gathered 50 years of rainfall statistics, and

compared those observations to predictions made by computer

simulations of the 20th century climate.
http://climateprogress.org/2010/06/14/ncar-trenberth-global-warming-extreme-weather-rain-deluge/http://climateprogress.org/2010/06/14/ncar-trenberth-global-warming-extreme-weather-rain-deluge/http://climateprogress.org/2010/06/14/ncar-trenberth-global-warming-extreme-weather-rain-deluge/http://voices.washingtonpost.com/post-carbon/2011/02/green_house_gases_led_to_incre.htmlhttp://voices.washingtonpost.com/post-carbon/2011/02/green_house_gases_led_to_incre.htmlhttp://voices.washingtonpost.com/post-carbon/2011/02/green_house_gases_led_to_incre.htmlhttp://voices.washingtonpost.com/post-carbon/2011/02/green_house_gases_led_to_incre.htmlhttp://climateprogress.org/2010/06/14/ncar-trenberth-global-warming-extreme-weather-rain-deluge/


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Those simulations included the warming impact of the billions of tons of

carbon dioxide human society has pumped into the atmosphere.

The study found that observed increase in deluges cannot be explained

by natural internal fluctuations of the climate system alone, saidZwiers. In other words, only the addition of greenhouse gases to the

atmosphere explains why the United States and Canada have

experienced a dramatic increase in heavy downpours.

Large [rainfall] events are becoming larger, Zwiers said. His work

found that from 1951 to 1999, the probability of heavy downpours

becoming even more extreme grew by about 7 percent, a figure he

characterized as really substantial.

Richard Allan, a climate scientist at the University of Reading in

England who was not part of the study, called the method employed by

Zwiers very rigorous.

He added, Theres already been quite a bit of evidence showing that

there has been an intensification of rainfall events across the globe.

But until now there had not been a study that formally identified thishuman effect on precipitation extremes, Zwiers said. This paper

provides specific scientific evidence that this is indeed the case.

Note that these studies do not extend beyond the year 2000, so they

miss the hottest decade on record and the wettest year on record.

You can see some of the amazing photos from the 2000 UK floodshere.
http://www.guardian.co.uk/environment/gallery/2011/feb/16/floods-2000-climate-change-pictures#/?picture=371763964&index=1http://www.guardian.co.uk/environment/gallery/2011/feb/16/floods-2000-climate-change-pictures#/?picture=371763964&index=1http://www.guardian.co.uk/environment/gallery/2011/feb/16/floods-2000-climate-change-pictures#/?picture=371763964&index=1http://www.guardian.co.uk/environment/gallery/2011/feb/16/floods-2000-climate-change-pictures#/?picture=371763964&index=1


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Heres some more quotes from leading scientists via Seth BorensteinsAPstory:

Both studies should weaken the argument that climate change is a

victimless crime, said Myles Allen of the University of Oxford. He co-

authored the second study, which connected flooding and climate

change in the United Kingdom. Extreme weather is what actually

hurts people.

Jonathan Overpeck, a University of Arizona climate scientist, who

didnt take part in either study, praised them as sensible and

particularly relevant given the array of extreme weather that weve

seen this winter and stretching back over the last few years.

Put the two papers together and we start to see an emerging

pattern, said Andrew Weaver of the University of Victoria, who wasnt

part of either study. We should continue to expect increased flooding

associated with increased extreme precipitation because of increasingatmospheric greenhouse gas. And we have no one to blame but

ourselves.

Lets run through some of the other recent studies that support the

conclusion that human-caused global warming is making weather more

extreme:
http://www.forbes.com/feeds/ap/2011/02/16/science-us-sci-climate-floods_8312043.htmlhttp://www.forbes.com/feeds/ap/2011/02/16/science-us-sci-climate-floods_8312043.htmlhttp://www.forbes.com/feeds/ap/2011/02/16/science-us-sci-climate-floods_8312043.htmlhttp://www.guardian.co.uk/environment/gallery/2011/feb/16/floods-2000-climate-change-pictures?picture=371763973http://www.forbes.com/feeds/ap/2011/02/16/science-us-sci-climate-floods_8312043.html


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Study: Global warming is driving increased frequency of extreme wet or

dry summer weather in southeast, so droughts and deluges are likely to

get worse

A new study by a Duke University-led team of climate scientistssuggests that global warming is the main cause of a significant

intensification in the North Atlantic Subtropical High (NASH)

that in recent decades has more than doubled the frequency of

abnormally wet or dry summer weather in the southeastern

United States.

The modelsknown as Coupled Model Intercomparison Project Phase

3 (CMIP3) modelspredict the NASH will continue to intensifyand expand as concentrations of carbon dioxide and other

greenhouse gases increase in Earths atmosphere in coming

decades.This intensification will further increase the

likelihood of extreme summer precipitation variability

periods of drought or deluge in southeastern states in coming

decades, Li says.

And one of mycommentersposted this list in response to the

nonsensical quote by Pielke in the Wall Street Journal, Theres no

data-driven answer yet to the question of how human activity has

affected extreme weather. The first three may be the most relevant.

Some observational, modelling and observational and modelling studies

concerning the trends in temperature extremes and precipitation

intensity. I have limited myself to material that has been released since

2007 (when the last IPCC report was released); this is by no means a

complete list. Not all of them directly challenge the claim about human

activities affecting extreme weather, but I included them because theypoint to a coherent picture.

Zhang et al. (2007):Detection of human influence on twentieth-century

precipitation trends. (Nature)

We show that anthropogenic forcing has had a detectable
http://climateprogress.org/2010/10/28/global-warming-extreme-wet-dry-summer-weather-in-southeast-droughts-and-deluges/http://climateprogress.org/2010/10/28/global-warming-extreme-wet-dry-summer-weather-in-southeast-droughts-and-deluges/http://climateprogress.org/2010/10/28/global-warming-extreme-wet-dry-summer-weather-in-southeast-droughts-and-deluges/http://climateprogress.org/2010/10/28/global-warming-extreme-wet-dry-summer-weather-in-southeast-droughts-and-deluges/http://climateprogress.org/2011/02/11/the-world-bank-droughts-and-voodoo-economics/#comment-324978http://climateprogress.org/2011/02/11/the-world-bank-droughts-and-voodoo-economics/#comment-324978http://climateprogress.org/2011/02/11/the-world-bank-droughts-and-voodoo-economics/#comment-324978http://www.nature.com/nature/journal/v448/n7152/abs/nature06025.htmlhttp://www.nature.com/nature/journal/v448/n7152/abs/nature06025.htmlhttp://www.nature.com/nature/journal/v448/n7152/abs/nature06025.htmlhttp://www.nature.com/nature/journal/v448/n7152/abs/nature06025.htmlhttp://www.nature.com/nature/journal/v448/n7152/abs/nature06025.htmlhttp://www.nature.com/nature/journal/v448/n7152/abs/nature06025.htmlhttp://climateprogress.org/2011/02/11/the-world-bank-droughts-and-voodoo-economics/#comment-324978http://climateprogress.org/2010/10/28/global-warming-extreme-wet-dry-summer-weather-in-southeast-droughts-and-deluges/http://climateprogress.org/2010/10/28/global-warming-extreme-wet-dry-summer-weather-in-southeast-droughts-and-deluges/http://climateprogress.org/2010/10/28/global-warming-extreme-wet-dry-summer-weather-in-southeast-droughts-and-deluges/


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influence on observed changes in average precipitation within

latitudinal bands, and that these changes cannot be explained

by internal climate variability or natural forcing. We estimate

that anthropogenic forcing contributed significantly to observed

increases in precipitation in the Northern Hemisphere mid-latitudes,drying in the Northern Hemisphere subtropics and tropics, and

moistening in the Southern Hemisphere subtropics and deep tropics.

The observed changes, which are larger than estimated from model

simulations, may have already had significant effects on ecosystems,

agriculture and human health in regions that are sensitive to changes

in precipitation, such as the Sahel.

Christidis et al. (2011):The role of human activity in the recentwarming of extremely warm daytime temperatures. (J. Climate).

Our analysis is the first that attempts to partition the observed change

in warm daytime extremes between its anthropogenic and natural

components and hence attribute part of the change to possible causes.

Changes in the extreme temperatures are represented by the temporal

changes in a parameter of an extreme value distribution. Regional

distributions of the trend in the parameter are computed with and

without human influence using constraints from the global optimal

fingerprinting analysis.Anthropogenic forcings alter the regionaldistributions, indicating that extremely warm days have

become hotter.

Zwiers et al. (2010):Anthropogenic Influence on Long Return Period

Daily Temperature Extremes at Regional Scales.(J. Climate).

We therefore conclude that the influence of anthropogenic

forcing has had a detectable influence on extreme temperatures

that have impacts on human society and natural systems atglobal and regional scales. External influence is estimated to have

resulted in large changes in the likelihood of extreme annual maximum

and minimum daily temperatures. Globally, waiting times for extreme

annual minimum daily minimum and daily maximum temperatures

events that were expected to recur once every 20 years in the 1960s are

now estimated to exceed 35 and 30 years respectively. . In contrast,
http://journals.ametsoc.org/doi/abs/10.1175/2011JCLI4150.1http://journals.ametsoc.org/doi/abs/10.1175/2011JCLI4150.1http://journals.ametsoc.org/doi/abs/10.1175/2011JCLI4150.1http://journals.ametsoc.org/doi/abs/10.1175/2011JCLI4150.1http://journals.ametsoc.org/doi/abs/10.1175/2010JCLI3908.1http://journals.ametsoc.org/doi/abs/10.1175/2010JCLI3908.1http://journals.ametsoc.org/doi/abs/10.1175/2010JCLI3908.1http://journals.ametsoc.org/doi/abs/10.1175/2010JCLI3908.1http://journals.ametsoc.org/doi/abs/10.1175/2010JCLI3908.1http://journals.ametsoc.org/doi/abs/10.1175/2010JCLI3908.1http://journals.ametsoc.org/doi/abs/10.1175/2011JCLI4150.1http://journals.ametsoc.org/doi/abs/10.1175/2011JCLI4150.1


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waiting times for circa 1960s 20-year extremes of annual maximum

daily minimum and daily maximum temperatures are estimated to

have decreased to less than 10 and 15 years respectively.

Krishnamurthy et al. (2009): Changing Frequency and Intensity ofRainfall Extremes over India from 1951 to 2003. (J. Climate).

Statistically significant increasing trends in extremes of rainfall are

identified over many parts of India, consistent with the indications from

climate change models and the hypothesis that the hydrological cycle

will intensify as the planet warms. Specifically, for the exceedance of

the 99th percentile of daily rainfall, all locations where a significant

increasing trend in frequency of exceedance is identified also exhibit a

significant trend in rainfall intensity.

Teixeira and Satyamurty (2011): Trends in the Frequency of Intense

Precipitation Events in Southern and Southeastern Brazil during 1960-

2004. (J. Climate).

In both regions, annual heavy and extreme rainfall event frequencies

present increasing trends in the 45-year period. However, only in

Southern Brazil is the trend statistically significant. Although longer

time series are necessary to ensure the existence of long term trends,

the positive trends are somewhat alarming since they indicate thatclimate changes, in terms of rainfall regimes, are possibly under way in

Brazil.

Ding et al. (2009): Changes in hot days and heat waves in China during

1961-2007. (Int. J. Clim.)

Over most of China except northwestern China, the frequency of HDs

was high during the 1960s-1970s, low in the 1980s, and high

afterwards, with strong interannual variations. A remarkableincreasing trend of HDs occurred after the 1990s in all regions.

Rodda et al.(2009): A comparative study of the magnitude, frequency

and distribution of intense rainfall in the United Kingdom. (Int. J.

Clim).

Most noticeably, increases up to 20% have occurred in the north-west


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of the country and in parts of East Anglia. There have also been

changes in other areas, including decreases of the same magnitude over

central England. The implications of these changes are considered.

Kysel (2009): Recent severe heat waves in central Europe: how to viewthem in a long-term prospect? (Int. J. Clim).

Owing to an increase in mean summer temperatures, probabilities of

very long heat waves have already risen by an order of magnitude over

the recent 25 years, and are likely to increase by another order of

magnitude by around 2040 under the summer warming rate assumed

by the mid-scenario. Even the lower bound scenario yields a

considerable decline of return periods associated with intense heat

waves. Nevertheless, the most severe recent heat waves appear to betypical rather of a late 21st century than a mid-21st century climate.

Gallant and Karoly (2010): A Combined Climate Extremes Index for the

Australian Region (J. Climate)

Over the whole country, the results show an increase in the extent of

hot and wet extremes and a decrease in the extent of cold and dry

extremes annually and during all seasons from 1911 to 2008 at a rate of

between 1% and 2% decade21. These trends mostly stem from changes

in tropical regions during summer and spring. There are relationshipsbetween the extent of extreme maximum temperatures, precipitation,

and soil moisture on interannual and decadal time scales that are

similar to the relationships exhibited by variations of the means.

However, the trends from 1911 to 2008 and from 1957 to 2008 are not

consistent with these relationships, providing evidence that the

processes causing the interannual variations and those causing the

longer-term trends are different.

Romps (2011): Response of Tropical Precipitation to Global Warming.

(J. Atmos. Sci.)

There are many properties of convection that can change as the

atmosphere warms, each of which could produce deviations from CC

scaling. These properties include the effective water-vapor gradient,

cloud pressure depth, and cloud velocity. A simple theory is developed


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that predicts the changes in these properties consistent with CC

scaling. Convection in the cloud-resolving simulations is found to

change as predicted by this theory, leading to an ~20% increase in local

precipitation fluxes when the CO2 concentration is doubled. Overall, an

increase in CO2 leads to more vigorous convection, composed of cloudsthat are wider, taller, and faster.

Wentz et al. (2007): How Much More Rain Will Global Warming Bring?

(Science).

Climate models and satellite observations both indicate that the total

amount of water in the atmosphere will increase at a rate of 7% per

kelvin of surface warming. However, the climate models predict that

global precipitation will increase at a much slower rate of 1 to 3% perkelvin. A recent analysis of satellite observations does not support this

prediction of a muted response of precipitation to global warming.

Rather, the observations suggest that precipitation and total

atmospheric water have increased at about the same rate over the past

two decades.

Allan et al. (2010): Current changes in tropical precipitation.

(Environmental research letters).

Analysing changes in extreme precipitation using daily data within thewet regions, an increase in the frequency of the heaviest 6% of events

with warming for the SSM/I observations and model ensemble mean is

identified. The SSM/I data indicate an increased frequency of the

heaviest events with warming, several times larger than the expected

Clausius-Clapeyron scaling and at the upper limit of the substantial

range in responses in the model simulations.

Allan and sodden (2008): Atmospheric Warming and the Amplificationof Precipitation Extremes. (Science).

We used satellite observations and model simulations to examine the

response of tropical precipitation events to naturally driven changes in

surface temperature and atmospheric moisture content. These

observations reveal a distinct link between rainfall extremes and

temperature, with heavy rain events increasing during warm periods


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and decreasing during cold periods. Furthermore, the observed

amplification of rainfall extremes is found to be larger than that

predicted by models, implying that projections of future changes in

rainfall extremes in response to anthropogenic global warming may be

underestimated.

Lenderink and Meijgaard (2008) Increase in hourly precipitation

extremes beyond expectations from temperature changes. (Nature).

Indeed, changes in daily precipitation extremes in global climate

models seem to be consistent with the 7% increase per degree of

warming given by the Clausius-Clapeyron relation3, 4, but it is

uncertain how general this scaling behaviour is across timescales. Here,

we analyse a 99-year record of hourly precipitation observations fromDe Bilt, the Netherlands, and find that one-hour precipitation extremes

increase twice as fast with rising temperatures as expected from the

Clausius-Clapeyron relation when daily mean temperatures exceed

12C. In addition, simulations with a high-resolution regional

climate model show that one-hour precipitation extremes increase at a

rate close to 14% per degree of warming in large parts of Europe. Our

results demonstrate that changes in short-duration precipitation

extremes may well exceed expectations from the Clausius-Clapeyron

relation.

Of course, dont missTable 3.8in the IPCCs Fourth Assessment,

Working Group I: The Physical Science Basis.

Finally, we have one of my favorites,Record high temperatures far

outpace record lows across U.S.:
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-8-5.html#table-3-8http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-8-5.html#table-3-8http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-8-5.html#table-3-8http://climateprogress.org/2010/02/11/science-meehl-ncar-record-high-temperatures-record-lows/http://climateprogress.org/2010/02/11/science-meehl-ncar-record-high-temperatures-record-lows/http://climateprogress.org/2010/02/11/science-meehl-ncar-record-high-temperatures-record-lows/http://climateprogress.org/2010/02/11/science-meehl-ncar-record-high-temperatures-record-lows/http://climateprogress.org/2010/02/11/science-meehl-ncar-record-high-temperatures-record-lows/http://climateprogress.org/2010/02/11/science-meehl-ncar-record-high-temperatures-record-lows/http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-8-5.html#table-3-8


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Spurred by a warming climate, daily record high temperatures occurred

twice as often as record lows over the last decade across the continental

United States, new research shows. The ratio of record highs to lows is

likely to increase dramatically in coming decades if emissions of

greenhouse gases continue to climb.

So yes, key weather events are becoming more extremeespecially

deluges, heat waves, and droughtsas climate scientists have long

predicted they would if atmospheric concentrations of greenhouse gases

kept rising. And now we have solid attribution of that increase in

extreme weather to human emissions in multiple independent studies.

So lets move on from that debate and focus on how we best minimize

the damage from future warmingaggressive greenhouse gas

mitigation plus adaptation.
http://www.ucar.edu/news/releases/2009/maxmin.jsphttp://www.ucar.edu/news/releases/2009/maxmin.jsphttp://www.ucar.edu/news/releases/2009/maxmin.jsphttp://www.ucar.edu/news/releases/2009/maxmin.jsphttp://www.ucar.edu/news/releases/2009/maxmin.jsphttp://www.ucar.edu/news/releases/2009/maxmin.jsphttp://www.ucar.edu/news/releases/2009/images/temps_2.jpghttp://www.ucar.edu/news/releases/2009/maxmin.jsphttp://www.ucar.edu/news/releases/2009/maxmin.jsphttp://www.ucar.edu/news/releases/2009/maxmin.jsphttp://www.ucar.edu/news/releases/2009/maxmin.jsphttp://www.ucar.edu/news/releases/2009/maxmin.jsp


13/13

Related Posts:

The year of living dangerously. Masters: The stunning extremeswe witnessed gives me concern that our climate is showing the

early signs of instability; Munich Re: The only plausibleexplanation for the rise in weather-related catastrophes is

climate change

Hansen: Would recent extreme events have occurred ifatmospheric carbon dioxide had remained at its pre-industrial

level of 280 ppm? The appropriate answer is almost certainly

not.
http://climateprogress.org/2010/12/23/the-year-of-living-dangerously-masters-weather-extremes-climate-change/http://climateprogress.org/2010/12/23/the-year-of-living-dangerously-masters-weather-extremes-climate-change/http://climateprogress.org/2010/12/23/the-year-of-living-dangerously-masters-weather-extremes-climate-change/http://climateprogress.org/2010/12/23/the-year-of-living-dangerously-masters-weather-extremes-climate-change/http://climateprogress.org/2010/12/23/the-year-of-living-dangerously-masters-weather-extremes-climate-change/http://climateprogress.org/2010/12/23/the-year-of-living-dangerously-masters-weather-extremes-climate-change/http://climateprogress.org/2010/10/01/hansen-extreme-events-2010-2012-record-high-global-temperature/http://climateprogress.org/2010/10/01/hansen-extreme-events-2010-2012-record-high-global-temperature/http://climateprogress.org/2010/10/01/hansen-extreme-events-2010-2012-record-high-global-temperature/http://climateprogress.org/2010/10/01/hansen-extreme-events-2010-2012-record-high-global-temperature/http://climateprogress.org/2010/10/01/hansen-extreme-events-2010-2012-record-high-global-temperature/http://climateprogress.org/2010/10/01/hansen-extreme-events-2010-2012-record-high-global-temperature/http://climateprogress.org/2010/10/01/hansen-extreme-events-2010-2012-record-high-global-temperature/http://climateprogress.org/2010/10/01/hansen-extreme-events-2010-2012-record-high-global-temperature/http://climateprogress.org/2010/10/01/hansen-extreme-events-2010-2012-record-high-global-temperature/http://climateprogress.org/2010/12/23/the-year-of-living-dangerously-masters-weather-extremes-climate-change/http://climateprogress.org/2010/12/23/the-year-of-living-dangerously-masters-weather-extremes-climate-change/http://climateprogress.org/2010/12/23/the-year-of-living-dangerously-masters-weather-extremes-climate-change/

Documents

Human Emissions Fuel Extreme Weather, Flooding That Harm Humans and the Environment