Download State of our Climate

State of our Climate
Prof. Daniel Cohan
Dept. of Civil & Environmental Engineering
[email protected]
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: 2014
2
Has Earth warmed?
Create your own time trends or spatial plots of temperature anomalies:
https://www.ncdc.noaa.gov/cag/time-series/global
3
Even stronger trends over
Northern Hemisphere land
https://www.ncdc.noaa.gov/cag/timeseries/global/nhem/land/1/2/1880-2016
Map of temperature anomalies
http://www.ncdc.noaa.gov/sotc/service/global/map-blended-mntp/201602.gif
Has Earth
warmed?
IPCC 2007 & 2013:
“Warming of the climate
system is unequivocal”
6
IPCC 2013
Additional evidence of warming
7
IPCC 2013
Global
US
8
National Geographic
Trends in Arctic sea ice
Minimum sea ice in 2015 (Sept 11)
vs. 1981-2010 median
Interactive sea ice graph
National Snow & Ice Data Center
Movie of Arctic sea ice trends
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: 2014
10
Greenhouse Gas Trends: CO2
IPCC WGI, Ch. 2, 2013
Website to plot trends in CO2 and other ghgs: NOAA
Radiative forcing since 1750
http://www.columbia.edu/~mhs119/Temperature/T_moreFigs/
Volcanos, ENSO drive annual variability
13
Could cuts in sulfur have
contributed to 2015 “T spurt”?
Cohan et al, submitted to Earthzine 2016
Warmth off coasts of North America
pre-dated & continued through El Niño
Cohan et al, submitted to Earthzine 2016
Ship emission
control areas
SO2 trends over China observed
by OMI satellite
2005-2007
2011-2014
Image Credit: NASA
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, 1983–2012 was likely the
warmest 30-year period of the last 1400 years” 18
Working Group I, Summary for Policymakers
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: 2014
19
Projected T and CO2 emissions
20
IPCC 2013
IPCC Emission Scenarios and
associated T and Sea Level predictions
Note: 2011 CO2 emissions = 9.26 GtC
Continuing this 2012-2100 would be 825 GtC (close to RCP 4.5)
IPCC
2013
21
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
Sea Level Rise Projections
23
IPCC 2013
Amounts of warming and melting depend
on how much more CO2 we emit
Winkelmann
et al., Advances in Scienc
24
NASA video on sea level rise
http://www.nasa.gov/press-release/nasa-science-zeros-in-on-ocean-risehow-much-how-soon
25
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
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: 2014
27
U.S. Greenhouse Gas Emissions
28
US EPA
Costs of CO2 mitigation options
29
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
Example “Wedges”
31
http://cmi.princeton.edu/wedges/
Pacala and Socolow, Science, 2004
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
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
Lenton and Vaughan, Atmospheric Chemistry and Physics Discussions, 2009
Geoengineering
34
Air Quality Overview:
Pollutants and Trends
35
Air pollution emissions declined
even as economy grew
36
US EPA: Our Nation’s Air: Status and Trends
NO2 trends observed from space
37
UC Berkeley BeHR data
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
Ozone (O3): Good up high,
bad nearby
39
Ground-level ozone “smog”
CO2, etc.
HO2
NO
CO, VOC
OH
NO2
VOC
Volatile
Organic
Compounds
O3
Secondary
NOx
Nitrogen
Oxides
O3
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
Ground-level ozone “smog”
pollution in Texas
75 ppb
standard
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
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
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
Particulate Matter
46
Image from www.collegesherbrooke.qc.ca/~graphycs/martinaube.html
47
US EPA
PM Health Effects
48
Pope et al., JA&WMA 2006
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
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