William K. M. Lau

Senior Scientist

NASA/DOE/ U. of Maryland

The Asian Monsoon and Climate Change

William K. M. Lau

Senior Scientist

Earth System Science Interdisciplinary Center

(ESSIC)

Joint Global Change Research Institute

(JGCRI)

NASA/DOE/U. of Maryland

USA

The Asian Monsoon Climate System

- Derived from “Mausum”, Arabic word for season - Knowledge of monsoon winds used for ocean navigation by early Arabian seafarers; Chinese Admiral, Zheng He (1371-1433) “Seven Expeditions to Southeast Asia/ East Africa” during the Ming Dynasty - First scientific studies of monsoon date back to Halley (1686), Hadley (1735) - Sir Gilbert Walker [1868-1958) discovered the Southern Oscillation (Walker Circulation) and used it to predict Indian Monsoon in 1930’s

JJA DJF (reversed)

Admiral Zheng He (1371-1433)

The Seven Expeditions to S. E Asia by Admiral Zheng He

Sir Gilbert Walker 1868-1958

Predicting the Indian monsoon with the Southern Oscillation Index

Critical timelines in modern era monsoon research: - 1950’s Modern studies using observations from global radiosonde network - 1970’s Global general circulation modeling of large-scale monsoon - 1980’s Satellite observations and data assimilations - 1990’s Coupled ocean-land-atmosphere global models global monsoon systems - 2000’s Earth System Models; downscaling using high-resolution region climate models, and cloud resolving models - 2010’s Human-nature interactions, multi-disciplinary, trans- interdisplinary, policy relevant studies, high resolution ESMs, super high performance computers, big data …

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D ~ +40% for CO2, +200% for CH4, + 40% for N2O

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DT ~ 1o C

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A fundamental change pattern of the global water cycle in a warmer world

More extreme precipitation events, more severe/prolonged droughts around the world

as the global ocean-atmosphere circulation adjusts to climate change

CMIP5 models predict that global dryness (i.e., prolonged severe drought, wildfires) is likely the first warning of global warming effect

on regional water cycle with major societal impacts.

Lau and Kim, 2015, Robust changes in the Hadley Circulation and Global Dryness from CMIP5 model projections, PNAS Lau et al., 2013: A canonical response in rainfall characteristics to global warming, GRL Lau and Kim 2012: The 2010 Russian wildfires and Pakistan flood : Teleconnection of Extremes. J. Hydroclimate.

Present Climate

Warmer Climate

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GDP growth and energy demands by types in China

gas

oil

coal

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• Surface temperature over China has increased by more

2oC since 1900, increasing by more than 0.3 degree per

decade since 1980. About 30-50% of the increase may

have been masked by aerosols.

• The average depth of the permafrost over northern Asia,

and glacier coverage over high mountain regions including

the Tibetan Plateau have shrunk by 5-10% in the last 30

years

• Temperature over Asia will rise by additional 3-5oC in the

21st century, depending on various emission scenarios, and

even with stabilization (450 ppm by 2050), temperature will

continue rising at about 0.4oC per 100 years, in the next

century. Climate Assessment Report Beijing Climate Center, 2012

Changes in Global Monsoon (IPCC 2013)

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Climate Change Hazards in Asia

Industrialization

smok

Dust storm

- Temperature (atmosphere, surface, ocean) - Moisture - Large-scale circulation - Convection, cloud radiation feedback -

GHG warming Aerosols Land use and changes..

- Floods/droughts - Heat waves - Severe weather - Pollution - Dust storms - Wild Fires - Glacier melt..

Forcing Monsoon Processes

Consequences

Global monsoon system and climate change

Natural variability: PDO, AMO, ENSO... Volcanic eruption

Back Up

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An alternate emission control scenario for climate change:

making the case for emission controls of BC and short-lived greenhouse gases

UNEP Report: Integrated Assessment of Black Carbon and Tropospheric O3 , 2010

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For climate change mitigation in Asia, the follow strategy is recommended:

Short-term strategy: emission control for BC and O3 precursors (CH4, CO NOx, VOCs…), now to next 20 years

Long-Term Strategy: emission control for CO2, now to next 50 years and beyond

- Reducing black carbon and CH4 and BC now will slow the rate of global warming by more than 30% within the first half of this century.

-A relative small number of emission reduction measures targeting black carbon and ozone precursors could immediately begin to protect climate, public health, water and food security, and ecosystems.

-Technology already exist for short-term strategy, but needs more aggressive enforcement.

- Implementation of the key critical measures would have substantial benefits for the Asian monsoon region especially the Himalayas and other glaciated and snow-covered regions.

-Both near-term and long-term strategies are essential to protect climate.

What can we do as educator, and researcher?

Seek better understanding of the science of climate change

• Organize international research efforts in space and in-situ observations

• Integrate modeling and observations

Increase education and outreach on climate change

• Introduce earth sciences early on to K-12

• Establish climate change interdisciplinary centers in colleges/universities: seek infusion of talents from traditional core disciplines

• “True-to-Science” public communication – science story writing; internet social network, films, arts, multi-media…

Mitigation and adaptation planning

• Educate and work with government, private sector, and stake-holders to promote sustainable development including improved climate change related hazard forecasts; conservation and new technology for alternate energy to reduce pollution and emission.

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COWL = 0.6oC (Pre-Industrial) = + 0.8oC, (All) = + 1.1oC (GHG only) = -0.3oC (inferred aerosol effect)

GHG

ALL

“inferred aerosol”

Nat

Time series of JJA COWL effect (DTLS , 10S-30N)

CMIP5 multi-model ensmeble simulations of 20th century surface temperature (with zonal mean removed)

Cold-Ocean-Warm-Land (COWL) +ve Dmonsoon

CMIP 5 model results do not match well with observations

Possible reasons for discrepencies between MMM

model 20th century simulations and observations

• Multi-decadal scale natural variations in real

world may mask global warming signal

• Poor physics (convection, aerosol-cloud

microphysics, cloud feedback, ocean-atmosphere

coupling….), and

• Current GCM resolutions (>1 x 1 degree lat-long)

are too coarse to resolve orographic forcing of

monsoon winds, and trapping of aerosols by local

topography.

Long-term rainfall trends in Asia

Possible causes: GHG warming, natural variability (ENSO, PDO, NAO…), aerosols, land use and change…

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Climate Change and Earth System Science