Download Evolution of the climate science

Climate Change
&
Development
Chandra Bhushan
New Delhi
Climate Science
Evolution of international climate
policy
1979: First World Climate Conference organised by WMO
1988: NASA scientist James Hansen tells U.S. Congress global
warming "is already happening now''
Creation of the IPCC by WMO & UNEP
1992: UNFCCC signed to based on CBDRRC
1997: UNFCCC parties approve Kyoto Protocol mandating
emission cuts by industrial nations
2005:Kyoto Protocol takes effect
2007:Bali Action Plan for binding agreement
2009:Copenhagen fiasco
2010:Cancun agreement – legitimizing Copenhagen
Evolution of the climate science
Awareness and partial understanding of the interactive
processes that govern climate change predate the IPCC,
often by many decades
Deeper understanding and quantification of these
processes have progressed rapidly since the IPCC First
Assessment Report (1990)
 These advances have arisen from new data, more
sophisticated analyses of data, improvements in
understanding and simulation of physical
processes and more extensive exploration of
uncertainty ranges
Evolution of the climate science
 IPCC First Assessment Report (1990)
 The Second Assessment Report (1996)
 The Third Assessment Report (2001) widely known for
projections and demand for adaptation
 The Fourth Assessment Report (2007) - over 90%
probability that this global warming is primarily caused by
human activities
 AR4 is old now – new observations, new science and
new projections and predictions
“Warming of the climate system is
unequivocal”
“Over 90% probability that this global
warming is primarily caused by human
activities – the most important of these
being the emission of greenhouse gases
and the clearing of natural vegetation”.
- IPCC Fourth Assessment Report
Observed changes
Global average
temperature
Global average
sea level
Northern hemisphere
snow cover
Observed changes
Hockey stick Curve
Correlating Global
average near-surface
temperature with
CO2 concentration in
the atmosphere
The frequency of heavy precipitation events has
increased over most land areas
- Rainfall in Mumbai (India), 2005:
1 million people lost their homes
The proportion of tropical cyclones reaching higher
intensity have increased over the past 3 decades
- Cyclone Nargis in Myanmar, 2008:
100 000 estimated deaths
Heat waves have become more frequent
over most land areas
- Heat wave in Europe, 2003: 35 000 deaths
Heat waves have become more frequent
over most land areas
- Heat wave in Europe, 2003: 35 000 deaths
“Continued GHG emissions [...] would
induce many changes in the global climate
system during the 21st century that would
very likely be larger than those observed
during the 20th century”
- IPCC Fourth Assessment Report
Ranges for predicted surface
warming
year
Continued emissions would lead to further warming
of 1.1ºC to 6.4ºC over the 21st century
(best estimates: 1.8ºC - 4ºC)
Changing impact assessment
2°C-Guardrail
(Smith et al. 2009 PNAS)
Projections and observations in line
Changes in global average surface air temperature relative to
1990. The blue line represents data from Hadley Center, UK; the
red line is NASA-GISS data. The broken lines are projections
from the IPCC TAR, with the shading indicating the uncertainties
around the projections.
Exceeding projections; changing
science
Change in sea level from 1970 to 2008, relative to the sea level
at 1990.
Change in Ocean temp. a better indicator
than changes in air temperature
Ocean store largest amount of heat; is a better indicator of change in
the climate than changes in air temperature. Current estimates
indicate that ocean warming is about 50% greater than had been
previously reported by the IPCC, this explains rapidly rising sea level
– thermal expansion.
Global mean sea level rises
The Greenland ice sheet
has been losing mass at a
rate of 179 Gt/ yr since
2003. This rate of loss
corresponds to a
contribution to global mean
sea level rise of 0.5 mm/yr;
the current total global mean
sea level rise is 3.1 mm/yr.
The new observations of the increasing loss of mass from glaciers,
ice caps and the Greenland and Antarctic ice sheets lead to
predictions of global mean sea level rises of 1 m (±0.5 m) during the
next century; about double the IPCC projections from 2007.
Feedbacks – Water Vapour
• Processes that are induced by climate change and that
subsequently drive further warming.
• Water vapour is the most abundant greenhouse gas and
makes the greatest contribution to the natural greenhouse
effect on Earth.
• Because the atmosphere’s ability to contain water vapour
is strongly dependent on temperature, the amount of
water vapour in the atmosphere is regulated by the
Earth’s temperature itself, increasing as warming occurs.
• This means that water vapour follows and amplifies
changes in global temperature that are induced by other
causes.
Feedbacks – Ice Cover
• Rapid reduction in the area of Arctic sea ice in summer. In
2007, the minimum area covered decreased by about 2
million square kilometres as compared to previous years.
In 2008, the decrease was almost as dramatic – Not
covered by IPCC.
• Ice and snow reflect most of the radiation from the sun
back into the atmosphere while seawater absorbs most of
the radiation reaching it from the sun.
• An ice-free ocean absorbs more heat than an ice-covered
ocean, so the loss of sea ice creates a “feedback” in the
climate system that increases warming.
Feedbacks – Sinks
• Important feedback - “carbon sinks” - processes that absorb
CO2 from the atmosphere.
• Over half of the CO2 emitted to the atmosphere by fossil fuel
combustion and land use change is removed by land and
ocean CO2 sinks. So, instead of CO2 conc. rising from 280
ppm in pre-industrial era to 500 ppm, it has risen to only 385
ppm.
• The fraction of human-driven CO2 emissions removed by these
sinks has decreased over the last 50 years and are decreasing
further.
• Several effects: increasing ocean acidification, ocean
circulation changes, and water, temperature, and nutrient
constraints on land CO2 uptake.
• Also, danger of inert carbon pools mobilisation and released
into the atmosphere either as CO2 or methane - peatland
carbon, in Arctic permafrost, which are vulnerable to warming.
Tipping points
Climate Politics
The 2°C target
1. If annual emissions remain at today’s level,
greenhouse gas levels would be close to 550
ppm by 2050
2. This would mean temperature increase of 35°C
3. The difference in temperature between the last
ice age (3 million years ago) and now is 5°C
4. The 2°C target is feasible; but it will require
unprecedented global cooperation.
Drastic reduction needed: For 450
ppm (2°C) reduce 80-90% by
2050
3-truths: Climate change political and
economic challenge
1. Is related to economic growth. No one has
built a low carbon economy (as yet)
2. Is about sharing growth between nations and
between people. The rich must reduce so that
the poor can grow. Create ecological space.
3. Is about cooperation. If the rich emitted
yesterday, the emerging rich world will do
today. Cooperation demands equity and
fairness. It is a pre-requisite for an effective
climate agreement.
CO2 emissions linked to energy and
linked to economic growth
Historical emissions - 1840-2006:
A tonne of CO2 emitted in 1840 same
value as tonne of CO2 emitted in 2008
Since 1840, 7 out
of every 10
tonnes of CO2
have been
emitted by the
rich countries
Historical emissions amount to about 1100 tonnes of CO2 per capita
for the UK and the US, compared with 66 tonnes for China and 23
tonnes for India
Is India and China the new villain?
•Between 1980-2005, the total
emissions of the US were
almost double that of China
and more than seven times
that of India.
•With just 15 per cent of the
world population, rich
countries account for 45 per
cent of CO2 emissions
1 US citizen =
•
•
•
•
107 Bangladeshis
134 Bhutanese
19 Indians
269 Nepalese
• Unacceptable. Need to secure ecological space
for growth
Kyoto: High on rhetoric. Low on
action
1.
Kyoto agreed to small change – 5% cuts
2.
Even that failed. US walked out. Emissions from Annex
I countries increased
Decreased 1.3% only because of
decrease of economies under transition.
The CO2 emissions
from industrialized
countries excluding
economies in transition
have increased by 14.5%
since 1990.
Cancun
•
Manufacturing Consent --- threat, bribe and
deals -- Wikileaks
•
Cancun Agreement – Voluntary pledge and
review, Kyoto protocol on death bed, promise of
US$100 billion
•
Climate in jeopardy