GLOBAL WARMING

What impact will it have on the world?

And what impact will it have on me?

Future Climate ChangeFuture Climate Change

What are the likely climate changes during this century?

-global temperature increase

-change in precipitation distribution

-sea level rise

-glacier/sea ice melting

- ocean acidification

• What factors will likely control the magnitude of climate change?

-population and economic growth

-CO2, CH4 and SO2 (aerosol) emissions and response of clouds

-success of mitigation efforts

The Real Announcement of THE END OF THE WORLD

IT WON’T LOOK LIKE THIS

IT WILL LOOK A LOT LIKE THIS

Is Global Warming real?

YES - GLOBAL TEMPERATURES HAVE SHOWN AN AVERAGE INCREASE OF ABOUT 1.5°F (0.76°C) OVER THE PAST 100 YEARS.

Why are a few degrees °C a big deal?

The temperature varies more than that between night and day; summer and winter!

Because we are talking about global temperature averages,

NOT weather.

For comparison;

some global temperature differences:

Last glacial maximum: - 4°C [20,000 years BP]

Western Washington

Cretaceous Hot House (palm trees and alligators in the Arctic Ocean) + 10°C [100 million years BP]

Barrow Alaska

WHY IS THE GLOBAL CLIMATE WARMING?

Global temperatures are controlled by the amount of GREENHOUSE

GASES in the atmosphere.

These gases are the ‘THERMOSTAT’ of the earth.

The main greenhouse gases are…

WATER CO2 METHANE

NITROUS OXIDE CFCs (freon)

What are “GREENHOUSE GASES”? And where do they come from?

And these have both natural and man-made sources

If there were NO Greenhouse gases in the atmosphere, the global temperature would be -15°C, instead of the present +15°C.

And this has happened in the past (+ 1 billion years ago).It is called ‘SnowBall Earth’ – and the oceans froze solid.

How have greenhouse gases changed recently? How have greenhouse gases changed recently? COCO22 concentrations over the last 10,000 years concentrations over the last 10,000 years

NOW

Are humans responsible for Global Warming?

There ARE natural variations in climate.

For example, there have been about 20 ‘switches’ between GLACIAL AND INTERGLACIAL PERIODS in the late 2 million years. Like a CLOCK.

NOW

But we know what causes these natural swings between glacial and inter-glacial periods.

They are caused by variations in the earth’s orbit around the sun and changes in the tilt angle of the earth.

And, being astronomical, they change regularly,

Like a clock - COLD for 100,000 years, then WARM for 4000 or 5000 years.

By this astronomical ‘clock’ (known as Milankovitch cycle),

we should be in another ICE AGE!

But – we aren’t.

sun

Global Sea Level has increased in the recent past –Global Sea Level has increased in the recent past – by about 10 cm (i.e., 4 inches) by about 10 cm (i.e., 4 inches)

Estimated Sea Level Rise from Total Loss of Ice Sheets - (with no sea water temperature change)

Sea Level Rise projection for 2000 to 2100 = 0.1 to 0.88 meters

E + W Antarctic Ice Sheet = 70 meters

West Antarctic Ice Sheet = 5 meters

Greenland Ice Sheet = 7 meters

But – don’t become too complacent with the old (i.e., 2006) models:

New data indicates that the ice discharge from many major Greenland ice streams has accelerated markedly.

During the Eemian Period (the last warm inter-glacial period, 125,000 years ago),

global temperatures were +3°C higher and sea level was +5 meters higher.

NOWwarmer

colder

Sea Level Rise of 3 meters in NE U.S. – red areas are underwater.

What is going on in the Arctic and Antarctic?

Why does everyone get excited about a little ice melting there?

BECAUSE, THE WAY THE GLOBAL CLIMATE WORKS, THE CHANGES IN THE POLAR REGIONS ARE ABOUT 2x LARGER (and therefore quicker) THAN FOR THE REST OF THE WORLD.

In the geological past, when climate has ‘changed’, the major change is in the Arctic/Antarctic, with much less change occurring at equatorial latitudes.

That is what the models predict, and that is what we are seeing now.

Change in Arctic Ice Cap, from 1979 to 2005.

Models predict that all arctic ice will be gone during the summer in less than 100 years.

Summer Arctic sea ice is shrinking at a rate of 9% per decade.

Last summer (2007), arctic sea ice cover was 43% of historical normal.

Clear signs of melting permafrost are already common in the Arctic.

However, just warming-up globally is not our only worry.

Rainfall distribution will change.

Bottom line: areas that are wet – will get wetter.

Areas that are dry – will get (a lot) dryer.

Below is what you and I (in the U.S.) are emitting right now. U.S. CO2 emissions by ‘product’

total

coal

gas

oil

Global use of coal is dramatically increasing; China is putting 2 new major coal-fired power plants on-line each week; and is scheduled to put 200 more on-line in next 10 years.

We however (the U.S.), are only planning for 1 new coal fired power plant coming on-line, each week.

The average person in the world today releases about 25 pounds (10 kg) of CO2 into the atmosphere – each day.

Beijing, 15 years ago

25 x 365 days = 9125 lbs = 4.5 tons/year

Beijing, last August

120 x 365 days = 43,800 lbs = 21.9 tons/yr.

About 5 times the global average.

The average American emits about 120 pounds of CO2 per day.

The scariest plot that I show in this class

We are here.

You will be here.

AMOUNT OF SPACE REQUIRED TO TRANSPORT THE SAME NUMBER OF PASSENGERS -

BY CAR, BUS, OR BICYCLE.

PREDICTIONS OF REDUCED AGRICULTURE PRODUCTION DUE TO GLOBAL WARMING DROUGHT

CONDITIONS

BY 2080.

EQUATORIAL AFRICA -50%

INDIA -40%

REMAINING AFRICA -30%

SOUTH AMERICA -20%

Think about what that means….

SHOULD WE PANIC?

While that can be exciting, there are more effective things to do.

What we decide to do in the next decade (transportation, housing, industry) will determine whether the equilibrium temperature in 100 years is either

+2.5°C or +8.0°C

But neither of these worlds will be particularly nice to live in and it will certainly be a different sort of world.

We actually get to choose which path we are on.

Business-as-Usual

Zero carbon footprint, starting tomorrow.

But the time to choose won’t last long.

Can’t we just “wait it out?” How long can this ‘warming’ last?

About 75% of CO2 emissions will have an average perturbation lifetime of 1800 years and 25% have lifetimes greater than 5000 years.

We get to decide the type of world – for our kids and grandkids;

but we have to decide pretty soon.

Is our current lifestyle the highest priority?

Or our kids?

End of the slides

But maybe not of the world.

Glo

bal

tem

pera

ture

s, °

C

Global Climate has been unusually stable – over the past 6000 years.

Nearly every glacier in the Cascades and

Olympics has retreated during the past 50-150

years

Photos courtesy of Dr. Ed Josberger, USGS Glacier Group, Tacoma, WA

South Cascade Glacier, 1928 (top)

and 2000 (right)

Spring snow pack is Spring snow pack is projected to decline as projected to decline as more winter precipitation more winter precipitation falls as rain rather than falls as rain rather than snow, snow, especially in warmer especially in warmer mid-elevation basinsmid-elevation basins

Snow pack will melt earlier Snow pack will melt earlier with warmer spring with warmer spring temperaturestemperatures

Lower Spring Snow packLower Spring Snow pack

+4°F, +4.5% winter precip

April 1 Snowpack

3 My ago, global temperatures were +3°C higher than present – and sea level was 25 to 35 meters higher than present.

[SO, if you raise the temperature +3°C, SL should rise about that much]

So our projected (minimum) increase in global temperature of 3.5°C should eventually produce about the same amount:

+20 to +35 meters of sea level rise.

But not right away….

Have these dramatic rises in Sea Level happened in the PAST?