The overwhelming majority of climate scientists are in agreement that the Earth is warming and that human actions play an important and fundamental role in this phenomenon. Furthermore, the climate is changing at an unprecedented rate and undoubtedly will bring changes during our lifetimes that many living organisms, including ourselves, may not be able to adapt to quickly enough to prevent a mass extinction.
The Intergovernmental Panel On Climate Change (IPCC) issued a report in November, 2007, verifying and detailing the climate changes which they foresee. It appeared briefly in some American media, but got a much more thorough airing in Asian and European outlets. Basically it stated that: (1) Climate Change is real, (2) It is mainly being caused by human activities, (3) in addition to increasing the Earth’s temperature, it is bringing about increases in catastrophic weather conditions, such as droughts, hurricanes, and tornados.
Worst of all, if we do not immediately begin ameliorative actions, world temperatures might increase by 6 – 9 degrees Fahrenheit before the end of the century. Such an increase, in so short a time, has never before been encountered by humans or any other living creatures. In my opinion as a biologist, I do not believe that life, as we conceive it, could continue to exist (KF).
Despite this dire news, climate deniers have kept up incessant campaigns of half-truths and lies, and most of us have gone back to sleep, probably because we could not bear to face the consequences of accepting the truth about climate change.
Below, you will find my summary of the very long and complicated IPCC – 4th Assessment Synthesis Report. If you care about the fate of the Earth or of your own children and grandchildren, you should read this or some other summary, and act on it.
INTERGOVERNMENT PANEL ON CLIMATE CHANGE – 4th ASSESSMENT
SYNTHESIS REPORT – November 16, 2007
[Summary by K. Fischman, Ph.D., Jan 21. 2008)]
(For treatment of Uncertainty & other notes, see Addendum on last page)
A. Observed Changes:
1. Warming of climate – unequivocal – now seen in increase of air & ocean temperatures, melting of snow & ice, sea level rise.
2. Northern Hemisphere temperatures – very likely higher than in last 500 yrs., & likely higher than in past 1,300 yrs.
3. Many natural systems are being affected, particularly by temperature increases.
4. Changes in Arctic & Antarctic systems – high confidence.
5. Increased runoff & earlier Spring runoff – high confidence.
6. Timing of Spring events is changing, & there is poleward & higher elevation shift in Plant & Animal ranges – very high confidence.
B. Causes of Changes:
1. Global Greenhouse Gas (GHG) emissions are due to human activities, & have increased since pre-industrial times. They have increased 70% since 1970.
2. Global atmospheric concentrations of carbon dioxide ( CO2 ), methane ( CH4), & nitrous oxide (N2O) have increased markedly since 1750 as a result of human activities. They far exceed pre-industrial values & earlier ones. This was determined by analysis of ice cores, spanning 650,000 yrs. The increase is primarily caused by fossil fuel use.
(a) CH4 has increased through agriculture & fossil fuel use.
(b) N2O has increased through agriculture.
3. Increase in global temperature – very likely caused by anthropogenic (human-caused) activities (otherwise, solar & volcanic activities would actually have cooled the planet over the past 50 yrs.)
4. Discernable human activities have resulted in other climate changes.
(a) Sea level rise – very likely.
(b) Wind patterns, storm tracks, hot nights & days, heat waves, droughts, & heavy precipitation.
5. Significant warming has been global (It is very unlikely that it is caused by natural variability).
C. Projected Climate Change & its Impacts:
1. There is high agreement & much evidence that with current climate change mitigation policies, Global GHG emissions will continue to increase over the next few decades.
2. Predicted global GHG emissions will grow by 25 -90% CO2-eq (CO2 equivalents) between 2000 – 2030 (23 yrs from now).
3. Climate changes in the 21st century (next 93 yrs.) are very likely to be larger than during the 20th century.
4. Global temperature will increase 0.8°F in the next 2 decades [almost a 1°F increase!].
D. Scenarios for GHG Emissions from 2000 – 2100 (in absence of enactment of climate policies)
1. Projected increased global surface warming & sea level rise in next 100 yrs:
(a) Best case – 3.8 °F increase & 6.9 – 14.6 ft. rise.
(b) Worst case – 5.9 °F increase & 10.0 – 22.ft. rise
[this does not include the full effects of Greenland & Antarctic ice sheet flow, which has increased dramatically in the last 4 yrs.)
(c) Worst case 13.6 °F (highest possible temperature)
[Would such a temperature be incompatible with most life?]
E. Regional Scale Changes:
1. Warming will be greatest over land & at most northern latitudes. This will result in contraction of snow cover, increase in thaw depth, & decrease in sea ice (It could disappear entirely in late summer).
2. There will be hot extremes, e.g. heat waves , heavy precipitation – very likely.
3. Tropical cyclone (Hurricane) intensity will increase. (There is less confidence that the #s of such events will increase).
4. There will be a poleward shift of extra-tropical storm tracks, with changes in wind, precipitation, & temperature patterns.
(a) increase in high northern latitudes – very likely
(b) decrease in most subtropical lands – likely
6. River runoff & water availability will increase in the higher latitudes, & will decrease in some dry regions of mid-latitudes & tropics. Many semiarid regions (e.g. Mediterranean, Western USA, southern Africa, & NE Brazil) will suffer decreases in water resources – high confidence.
F. Timing & Magnitude of Impacts (as well as amounts & rates of climate change): 1. (a) 30 % of species are at risk of extinction (best case)
(b) Significant worldwide extinctions (worst case)
2. Many other serious consequences associated with global temperature change – e.g.
• cereal productivity in low latitudes will decrease.
• coastal flooding
(high confidence for all of these)
G. Projected Regional Impacts (with very high confidence or high confidence):
1. Africa – 50 % decrease in rain-fed agriculture, & 5 – 8% increase of arid land.
2. Asia – decrease in freshwater availability, & flooding in mega delta regions. [e.g. Bangladesh]
3. Australia – significant biodiversity loss in the Great Barrier Reef & the Queensland Wet Tropics. Sea level rise will exacerbate the effects of coastal development & population growth. Agriculture & forestry are expected to decline.
4. Europe – increased risk of flash floods, coastal flooding, & erosion. Mountains – extensive species losses (up to 60%), glacier retreat, & reduced snow cover (Winter tourism will decrease). South Europe – is expected to experience high temperatures, drought, & decrease in crop production, as well as heat waves & wildfires.
5. Latin America – replacement of: tropical forest by savanna in eastern Amazonia, & semiarid vegetation by arid-land vegetation. There is risk of significant biodiversity loss & species extinction. Crops & livestock are projected to decrease in productivity, hunger increase, & water availability decrease.
6. North America – Western mountain regions expected to experience decrease in snow pack, increase in winter flooding, & reduced summer flows. Rain-fed yields in agriculture will increase 5 – 20%. Cities in some areas would have increases in #, intensity, & duration of heat waves.. Coastal communities & habitats would be stressed.
7. Polar Regions – Glaciers, ice sheets, & sea ice will decrease in thickness & extent. Detrimental stresses on migratory birds, mammals, & predators. Detrimental impacts on traditional indigenous life. Decrease in climate barriers, resulting in increase of invasive species.
8. Small Islands – Their existence threatened by: inundation, storm surge, & erosion. Coral bleaching. Water resources decrease, & invasion of non- native species increase.
H. Likely Effected By Climate Change:
(a) Tundra, boreal forests, & mountains.
(b) Mediterranean region – rainfall decrease, resulting in decrease of tropical rain forests.
(c) Coastal regions – Mangroves & salt marshes impacted.
(d) Coral Reefs – at high risk.
2. Water resources – dry regions in mid-latitudes, dry tropics, & areas that are dependant on snow & ice melt.
3. Low-latitude agriculture – decrease in water availability.
4. Low-lying coastal regions impacted by rise in sea level & extreme weather.
5. Human health – populations with low adaptive capacity impacted.
(a) Arctic – projected high rates of warming.
(b) Africa – low adaptive capacity.
(c) Small islands – sea rise & warming.
(d) Asian & African mega delta regions – sea levels, storm surges, & river flooding [what will happen to New Orleans, Miami, etc. in North America?]
I. Ocean Acidification:
1. Anthropogenic CO2 uptake – since 1750 [start of industrial age] has led to oceans becoming more acidic.
2. Projections – Decrease in global ocean pH of between 0.14 – 0.35 by the 21st century. [This is a large change because pH is a log, not an arithmetic function]
3. Already observed – Damage to marine, shell-forming organisms, including coral.
J. Frequencies & Intensities of Extreme Weather & Sea Level [Rise] Projected to Increase:
1. Temperature rise is virtually certain:
(a) Agriculture – Increased yields in colder environments, decreased yields in warmer ones, & insect outbreaks.
(b) Water sources – detrimental to those regions which rely on snow melt for water supply.
(c) Reduced human mortality due to decreased cold exposure.
(d) Reduced demand for heating, but increased demand for cooling. Decrease in air quality in cities, but reduced disruption of traffic in the winter.
2. Very Likely Outcomes:
(a) Warm spells & heat waves.
(b) Reduced agricultural yield in warmer regions, & increase in wildfires.
(c) Water quality – water demands increase, & quality decreases, more algal blooms.
(d) Heat-related mortality –especially in the young, aged, chronically sick, & the socially isolated.
(e) Quality of life –decrease in warm regions, especially among the very elderly, very young, & the poor.
3. Very Likely Outcomes – In areas where heavy precipitation occurs, results in:
(a) Agriculture – crop damage, soil erosion, & water logging of soils.
(b) Water resources – contamination, but water scarcity may be relieved.
(c) Human health – deaths, injuries, & diseases increase.
(d) Society – Disruption of settlements, commerce, infrastructure, & loss of property.
4. Drought increases:
(a) Agriculture – degradation, decreased yields, livestock deaths, & increased wildfires.
(b) Water – stress.
(c) Health – Food & water shortages, also water – & food-borne diseases.
(d) Society – Reduced hydroelectric power & increased population migrations.
5. Tropical Cyclone Activity Increases:
(a) Agriculture – crop & coral reef damage
(b) Water – power outages, causing public water supply disruption.
(c) Health – deaths, injuries, disease, & post-traumatic stress disorder.
(d) Society – more pressure for population migrations.
6. High sea level:
(a) Agriculture – damaged by salinization.
(b) Decreased fresh water availability.
(c) Health – deaths & injuries increase.
(d) Social – infrastructure damage & increased pressure for population migration & infrastructure relocation.
K. Anthropogenic (human-caused) warming & sea level rise would continue for centuries, even if GHG concentrations were to be stabilized.
L. Consequences of multi-century warming:
1. Contraction of the Greenland Ice Sheet, & perhaps its total elimination, is projected to result in a sea rise of 7 Meters (22+ ft.) within several thousand yrs.
M. Anthropogenic warming:
1. It could lead to abrupt & irreversible impacts, depending on the rate & magnitude of climate change:
(a) There could be meters of sea level rise, major changes in coastlines, & inundations of low-lying areas, such as deltas & islands, over several thousand years.
(b) However, more rapid changes in sea levels within the time frame of centuries cannot be excluded.
2. Extinctions (medium confidence):
(a) If warming exceeds 2.7 – 4.5 °F, 30% of species are likely to be at risk of extinction.
(b) If warming exceeds 6.3 °F, projections suggest there would be a significant # of extinctions (40 – 70% of species around the globe).
3. Meridianal Overturning Circulation (MOC) – (This is density-driven global circulation of oceans). It is very unlikely to undergo a large, abrupt transition during the 21st century. However, changes in it will likely have long-term effects on marine ecosystem productivity, fisheries, & oceanic oxygen concentrations.
4. Oceanic Uptake of CO2 – This would lower the pH, & in turn, it may feedback on the climate system.
N. Adaptation & Mitigation Options:
1. More extensive adaptation than is currently occurring is required to reduce vulnerability to climate change.
2. There is high confidence that there are viable adaptation options.
3. Adaptive capacity is connected to social & economic development, but is currently unevenly distributed.
4. There is high agreement & much evidence of substantial economic potential [benefit] for mitigation of GHG emissions. This could offset projected emissions or [even] reduce emissions below current levels.
N(1). Examples of planned adaptation:
(a) Rainwater harvesting & water storage.
(b) Adjustment of planting dates, change in crop variety, crop relocation, & tree planting.
2. Protection [& strengthening] of existing natural barriers [e.g. New Orleans marshlands].
3. Shifting ski slopes to higher elevations.
4. Redesign & relocation of rails, roads, & other infrastructure, & change of emphasis [toward more efficient transportation].
5. Increase in energy efficiency & switching to renewable sources, thus reducing our dependency on a single source.
6. Examples of planned mitigation:
(a) CO2 capture & storage (sequestration).
(b) Reduction of fossil fuel subsidies.
(c) Subsidies for renewable energy.
(d) Production & increasing use of fuel-efficient vehicles, mandatory fuel economy.
(e) Reduction in CO2 & N2O emissions.
(f) Reducing deforestation
(g) Use of forestry products for bioenergy [renewable].
O. Future Energy Infrastructure – The cost expected to exceed 20 trillion US dollars, between 2005 – 2030 [25 yrs.].
P. There are a wide variety of policies & instruments available to create incentives for mitigation activities.
Q. There is high agreement & much evidence that there are near-term co-benefits to offset a substantial fraction of mitigation costs.
R. There is high agreement & medium evidence that lifestyle & behavioral changes can contribute to climate mitigation.
S. There is high agreement & much evidence that international cooperation can reduce GHG emissions, e.g. Carbon markets.
T. It is very likely that climate change can slow progress toward sustainable development.
U. Science can provide criteria to judge ”dangerous anthropogenic interference with the climate system.”
V. There are 5 reasons for concern. These risks are identified with higher confidence than in the previous TAR (Third Assessment Report of the IPCC, 2001):
1. There are threats to unique & vulnerable systems. e.g. polar, mountains, & coral reefs.
2. There are risks of extreme weather. e.g. droughts, heat waves, & floods.
3. Distribution of impacts & vulnerabilities –uneven. e.g. poor, elderly, low latitude, less developed, dry areas, mega deltas.
4. Aggregate impacts – e.g. net costs are projected to increase with amount of warming & time.
5. Risks of large-scale singularities:
e.g. There is high confidence that sea level rise would be much greater than in the 20th century, due largely to the contributions of the Greenland & Antarctic ice sheets, & that this could occur in century time scales.
(Recent observations, not accounted for in this report, could raise the rate of ice loss).
W. There is high confidence that neither adaptation nor mitigation can avoid all climate change impacts, but they can significantly reduce them.
X. If climate change is not mitigated, it is likely to exceed the capacity of natural & human-managed systems to adapt to it.
Y. Many impacts can be reduced, delayed, or avoided by mitigation over the next 2 – 3 decades to achieve lower stabilization levels.
Z. Delayed GHG emission reductions significantly constrain opportunities to achieve lower stabilization levels, & increase the risk of more severe climate change impacts.
AA. In order to achieve the lowest mitigation scenario, emissions would need to peak no later than 2015 (7 yrs from now).
BB. Sea level rise, caused by warming, is inevitable:
(1) Even if GHGs were stabilized, thermal expansion (of oceans) would continue for several hundred yrs., causing an eventual sea level rise of several meters. This would be much greater than projected for the 21st century.
(2) The Greenland Ice Sheet could contribute several meters more to sea rise in addition to that produced by thermal expansion. This would occur if temperatures > 3.4 – 8.3 °F above the pre-industrial level are sustained over several centuries.
(3) Stabilization of GHG concentrations at, or above present levels would not stabilize sea levels for many centuries.
CC. Stabilization Scenarios & Their Effects On Temperature & Sea Level (Table SPM.6)
Scenario CO2 eq.(ppm) Temperature(°F) Sea Level(ft.)
Best (I) 350 – 400 3.6 – 4.3 1.3 – 4.5
Worst (VI) 660 – 790 8.8 – 11.0 1.8 – 11.8
(double pres. level)
• The table above shows effects from thermal expansion only. It does not take into account the additional contributions of ice sheets, glaciers, & ice caps to sea level & temperature. [It appears that temperatures in the Worst Case scenario could result in extinction of much life on Earth]
DD. There is high agreement & much evidence that emission stabilization levels can be achieved by deployment of technologies that are currently or soon to be available.
EE. Cost of Climate Change:
1. The impacts of climate change will very likely increase costs over time as the temperature rises.
2. There will be significant differences in costs among regions, populations, & sectors. Estimates of damage are very likely underestimates, due to inability to measure all of them. [e.g. social costs]
TREATMENT OF UNCERTAINTY:
Qualitative: (theory, observation, models)
1. high agreement, much evidence
2. high agreement, medium evidence
3. medium agreement, medium evidence
Quantitative: (expert judgment, statistics, probability of occurrence).
1. very high confidence (9 out of 10)
2. high confidence (8 out of 10)
3. medium confidence (5 out of 10)
Specific Outcomes: (expert judgment, statistics)
1. virtually certain (> 99%)
2. extremely likely (> 95%)
3. very likely (> 90%)
4. likely ( > 66%)
5. unlikely (< 33%)
6. very unlikely (< 10%)
7. extremely unlikely (< 5%)
8. exceptionally unlikely (< 1%)
Notes: 1. Treatment of uncertainty is highlighted in red
2. K. F.’s emphasis is indicated by bolding
3. Opinion is enclosed in square brackets [ ]
4. Numerical ranges are also in square brackets e.g. [1.8 – 6.3]
They indicate 90% uncertainty intervals:
(1) 5% likelihood – above range in brackets
(2) 5% likelihood – below range in brackets
1. IPCC 4th Assessment Report – Summary for Policy Makers