State of our Climate. Prof. Daniel Cohan Dept. of Civil & Environmental Engineering

Transcription

1 State of our Climate Prof. Daniel Cohan Dept. of Civil & Environmental Engineering

2 Four Key Questions about Climate Has Earth warmed? (Measurement) Why is it warming? (Attribution) How will climate change? (Predictions) What are our options? (Policy) Source for most slides: IPCC Fifth Assessment Report: Summary for Policymakers (draft): 2013 Technical sections:

3 Has Earth warmed? Create your own time trends or spatial plots of temperature anomalies: 3

4 Even stronger trends over Northern Hemisphere land

5 Map of temperature anomalies

6 Has Earth warmed? IPCC 2007 & 2013: Warming of the climate system is unequivocal 6 IPCC 2013

7 Additional evidence of warming 7 IPCC 2013

8 Global US 8 National Geographic

9 Trends in Arctic sea ice Minimum sea ice in 2015 (Sept 11) vs median Interactive sea ice graph National Snow & Ice Data Center Movie of Arctic sea ice trends

10 Four Key Questions Has Earth warmed? (Measurement) Why is it warming? (Attribution) How will climate change? (Predictions) What are our options? (Policy) Source for most slides: IPCC Fifth Assessment Report: Summary for Policymakers (draft): 2013 Technical sections:

11 Greenhouse Gas Trends: CO2 IPCC WGI, Ch. 2, 2013 Website to plot trends in CO2 and other ghgs: NOAA

12 Radiative forcing since 1750

13 Volcanos, ENSO drive annual variability 13

14 Could cuts in sulfur have contributed to 2015 T spurt? Cohan et al, submitted to Earthzine 2016

15 Warmth off coasts of North America pre-dated & continued through El Niño Cohan et al, submitted to Earthzine 2016

16 Ship emission control areas

17 SO2 trends over China observed by OMI satellite Image Credit: NASA

18 IPCC 2013 conclusions related to Has Earth warmed? Warming of the climate system is unequivocal Since the 1950s, many of the observed changes are unprecedented over decades to millennia The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen Each of the last three decades has been successively warmer at the Earth s surface than any preceding decade since 1850 In the N. Hemisphere, was likely the warmest 30-year period of the last 1400 years 18 Working Group I, Summary for Policymakers

19 Four Key Questions Has Earth warmed? (Measurement) Why is it warming? (Attribution) How will climate change? (Predictions) What are our options? (Policy) Source for most slides: IPCC Fifth Assessment Report: Summary for Policymakers (draft): 2013 Technical sections:

20 Projected T and CO2 emissions 20 IPCC 2013

21 IPCC Emission Scenarios and associated T and Sea Level predictions Note: 2011 CO2 emissions = 9.26 GtC Continuing this would be 825 GtC (close to RCP 4.5) IPCC

22 Predicted Changes in T and Precipitation Low emissions scenario IPCC 2013 High emissions scenario 22 Stippling: 90% of models agree on sign of change Hatching: Direction of change is highly uncertain between models

23 Sea Level Rise Projections 23 IPCC 2013

24 Amounts of warming and melting depend on how much more CO2 we emit Winkelmann et al., Advances in Scienc 24

25 NASA video on sea level rise 25

26 What if Sea Levels Rose 25 m? (Paleoclimate data may indicate that 3 C ~25 m sea level rise over many centuries) 26 Images from James Hansen

27 Four Key Questions Has Earth warmed? (Measurement) Why is it warming? (Attribution) How will climate change? (Predictions) What are our options? (Policy) Source for most slides: IPCC Fifth Assessment Report: Summary for Policymakers (draft): 2013 Technical sections:

28 U.S. Greenhouse Gas Emissions 28 US EPA

29 Costs of CO2 mitigation options 29

30 Socolow and Pacala, Scientific American, 2006 (and related Science paper) *Now need 8 wedges to stabilize at 500 ppm (vs. 850 ppm on current path) 30

31 Example Wedges 31 Pacala and Socolow, Science, 2004

32 Controlling non-co2 emissions Methane (rice paddies, landfills, cattle, etc.) Global warming potential (100-yr basis): 34 Co-benefits: Reduce tropospheric O3; cost-effective energy source (e.g., burn landfill gas) Black carbon (diesel vehicles, other combustion) Controls would reduce the regional scale warming of atmosphere caused by absorption Co-benefit: Reduce PM2.5 (health, visibility) Halocarbons (CFCs, HCFCs, HFCs) Very high global warming potential (100-over 10,000) Co-benefit: Protect stratospheric ozone 32

33 Adaptation IPCC 2007: Adaptation will be necessary to address impacts resulting from the warming that is already unavoidable due to past emissions. Adaptation alone is not expected to cope with all the projected effects of climate change, and especially not over the long term as most impacts increase in magnitude. Sustainable development can reduce vulnerability to climate change. Developing countries likely to face greatest challenges 33

34 Lenton and Vaughan, Atmospheric Chemistry and Physics Discussions, 2009 Geoengineering 34

35 Air Quality Overview: Pollutants and Trends 35

36 Air pollution emissions declined even as economy grew 36 US EPA: Our Nation s Air: Status and Trends

37 NO2 trends observed from space 37 UC Berkeley BeHR data

38 Ozone and Particulate Matter Non-Attainment US EPA sets ambient standards States must attain those standards Non-attainment drives priorities for policy, industry, and science 38 Source: Maps fromu.s. US EPA EPA

39 Ozone (O3): Good up high, bad nearby 39

40 Ground-level ozone smog CO2, etc. HO2 NO CO, VOC OH NO2 VOC Volatile Organic Compounds O3 Secondary NOx Nitrogen Oxides O3

41 Ground-level Ozone Impacts Health effects Strong oxidant, irritates lungs Linked to asthma and other respiratory illnesses Recently linked to mortality Damage to vegetation & crops Greenhouse gas Non-attainment of EPA standards 41

42 Ground-level ozone smog pollution in Texas 75 ppb standard

43 Steps forming high O3 in Houston Large releases of HRVOCs & NOx from Ship Channel Especially if upset conditions at a source Mix with NOx from city (mostly vehicles) Ozone forms in plume downwind 43

44 Mix of clean and exceedance days create moderate average for Houston 8-h ozone 44 US EPA, Health and Risk Exposure Assessment for Ozone, 2014

45 Particulate Matter Particulate matter: airborne particles composed of a variety of chemical compounds Large particles settle out quickly Fine particles (<2.5 μm (PM2.5)) cause greatest damage to visibility (haze) and human health (respiratory, cardio-vascular, mortality) 45

46 Particulate Matter 46 Image from

47 47 US EPA

48 PM Health Effects 48 Pope et al., JA&WMA 2006

49 Cohan analysis of TCEQ data compiled by US EPA Fine Particulate Matter (PM2.5) in Texas Fell to 11.8 in 2013 DVmonitor = 3-year average of annual average PM2.5 DVregion= max(dvmonitor in region) NAAQS limit = 12 μg/m3 49

50 Summary Climate The Earth is warming Greenhouse gases from fossil fuels are likely the leading cause Rate of further climate change depends on emissions Opportunities and challenges to controlling emissions Air Quality Dramatic improvements in air quality over Texas and U.S. Ozone and particulate matter continue to pose challenges for health and attainment