Climate facts and predictions from the IPCC

The basic science and forecasts from the fifth Intergovernmental Panel on Climate Change (IPCC) report by leading climate scientists.
Climate change activists spell out the challenge for delegates at the 2010 UN climate talks in .../ Credits: Reuters

Article at a glance

Here is the critical information and projections on climate change as outlined by ‘The Physical Science Basis’ of the IPCC’s Fifth Assessment on climate change.

Global warming is “unequivocal” and climate scientists are 95% certain that humans are the “dominant cause”. New evidence has increased this level of certainty from 90% in the last report in 2007.

"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, and the concentrations of greenhouse gases have increased," notes the report.

Climate change skeptics have suggested that changes in the sun’s radiation account for global warming. Although the IPCC scientists have found fluctuations in the sun's radiation, it says that these “have not contributed to the increase in global mean surface temperature over the period 1986 to 2008”.

Greenhouse gases carbon dioxide, methane, and nitrous oxide in our atmosphere have increased since pre-industrial times by 40%, 150%, and 20% respectively, due to fossil fuel use, deforestation, land use change and agriculture. These rates of increase are unprecedented in the last 22,000 years.

The massive recent increase has led to a rise of average temperatures by 0.85 degrees Celsius since 1880. Scientists say it is likely that the last 30 years has been the hottest period in the Northern Hemisphere for 1400 years.

The vast majority of that extra energy – over 90% between 1971 and 2010 – has gone into the oceans, leading to reduced Arctic sea ice, sea level rise and ocean acidification.

Even if we were to significantly reduce, or ‘mitigate’, carbon emissions and thereby limit CO2 levels to 421 parts per million by 2100 – in 2013, they topped 400ppm – we are likely locked into global temperature rise of 1.5 degrees by 2100. The worst-case high emissions scenario (1313ppm by 2100) foresees up to 4.5 degrees of warming.

Warming will not be equally distributed. Impacts will be more pronounced in northern latitudes. Arctic temperatures have increased faster than global average temperatures. By mid-century, the Arctic might well be ice-free in summer. Since 1979, it has lost 9.4% to 13.6% of summer ice per decade

Meanwhile, permafrost is also on the retreat in the Arctic. This has freed large amounts of methane, a greenhouse gas far more potent than carbon dioxide. By the end of the 21st century, the area of permafrost near the surface (upper 3.5 m) is projected to decrease by between 37% (low emissions scenario) to 81% (very high emissions scenario). Massive releases of methane could trigger runaway global warming, some scientists believe, but these kinds of amplification effects are not yet properly understood and so the IPCC report does not consider them.

Meanwhile glaciers all over the world are diminishing in volume. Excluding Antarctica, glaciers are expected to diminish in volume by up to 55% for the mitigation of emissions scenario and up to 85% for the very high emissions scenario by the end of the century.

Sea level rose 19 centimeters during the period 1901 to 2010, due largely to the fact that warm water has a larger volume than cold water, and also melting ice sheets and glaciers. Further sea level rise by the end of the century is projected to be up to 0.55m for the low emissions scenario and up to 0.98m for the very high emissions scenario. Even if carbon dioxide emissions can be stabilized, sea levels will keep on rising for centuries until the temperature gain reaches the ocean depths.

The IPCC also notes that weather extremes are becoming more common in particular regions, and also more intense. It is “virtually certain that there will be more frequent hot and fewer cold temperature extremes” and thinks it likely that there will be longer-lasting heatwaves in future as well as extreme heavy rainfall and longer monsoon seasons in some places.

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Comments (38)

dev dongol: 27.01.2012, 05:45

Dear Hari Prakash Sharma,

shall we share ideas through emails, please. dev.dangol@yahoo.co.uk

Hari Prakash Sharma: 26.01.2012, 06:13

IPCC Finding is entirely wrong. It has taken 15 long years to fight for the Green House Effect by giving wrong findings, It wiil take only one year to check out things byproper study. No body is ready to discuss things with me. Though I am projecting my view point every day to some scientific magazine.

Tassilyn: 01.11.2011, 03:09

So that's the case? Quite a revleatoin that is.

phiankla: 24.10.2011, 23:18

Put the temperature of Earth aside aside for a moment. Last I checked we all need oxygen to breath, and plants like trees and grasses give us that, and yes water does too through evaporation but if we had no plants left on earth and relied solely on the oceans for oxygen I highly doubt planet earth would be able to sustain even half of the worlds population. Only a small fraction of forests remain; we need fresh water to live, so does over ninety percent of the plant life on earth (above water). Fact- Forests create their own precipitation patterns through trans evaporation (they sweat) giving more fresh water to ares than say if it were a desert. Fact- desertification is on the rise globally; sorry but sattelite images taken over the last 20-30 years just doesn't lie. People living in affected areas will tell you the same. No one on earth can convince me that if people were not here doing the destructive things that we do, that desertification would still be on the same trend it is today. We are the cause, therefore we must be the solution or perish to ignorance and inaction. I would love to take action despite the ney-sayers; (who must be blinded by greed or living in a temperate climate where nothing seems to be wrong) anyone got a couple million bucks I can borrow. Fixing a broken planet isn't going to be cheap but at least future generations get to enjoy the fruits of our labour and not the trash of our carelessness.

dev dongol: 16.10.2011, 18:14

1.Green house is made using transparent solid materials – plastics or glasses. We cannot build a structure using fluids. (So gases can’t form a green house, thus no GHE due to gases).
2.The higher the altitude our climatic atmosphere, troposphere, is colder.
3.At 30,000 is -58 degree centigrade.
4.Heat transmission – always higher to lower temp. Heat reached upper region of the troposphere cannot come back to hotter places below.
5.Fluids (liquids and gases) by convection method of heat transmission deliver heat from hotter to colder zone. Thus air help the earth to cool down. This process goes on all the time but the process is not good enough to cool down the earth as the gases carry least amount of heat.
6.Troposphere is a homogenous mixture of gases, not layered. As the atmosphere is always moving up and down, to and fro the freely moving molecules can’t be layered. Had it been layered co2 would be at the bottom of the atmosphere i.e just above the earth’s surface. Then we are dead. We need o2 to be alive.
7.Air is a perfect transparent medium. It does not reflect light so we don’t see air. Opaque materials reflect light so we see them. If the air is opaque? We wouldn’t need eyes. There is no way for gases in the higher altitude to send heat back.
8.Closed room gets heated uniformly but upper part is warmer as hot air goes up. So if GHE due to gases were possible our atmosphere would be hotter at higher altitude.
9.a. it becomes cold immediately when it rains b. annual frequency of rain is decreasing. Reduced frequency of nature’s effective cooling system, the rain cycle, is causing the ‘global warming’.
10.Rain cycle is related to heat and evaporation only and nothing other factors. Plants have no role in making rain but holding water on earth by not allowing soil to dry quickly as surface without plants. Evaporation for regular rain cycle not from sea, lakes or rivers- not warm enough (4 billion yrs on) but from land surface. Why not more rain cycle nowadays? Warmer, sea surface area and temp increasing (favourable for evaporation)? Half portion of the earth is always exposed to the sun. Does not fluctuate temp seasonally (consistent) as land surface. Evaporation is reduced – human settlement covering land by houses, roads, pavements etc; deserts, and deforestation etc. evaporation of water can deliver maximum quantity of heat and reduce the temperature. So rain cycle needs new explanation.
11.Land surface changes temperature even on daily basis – hot during day time and cold during night (or seasonally as well) unlike sea or lakes or river water (they are always cold even in 4 billion years).
Thus global warming or climate change due to gases is impossible. No one has explained the reason nor can be explained scientifically. Instead of warming gases are cooling the earth by convection method of heat transmission all the by nature and man has no control over the process.
Causes and solution: by keeping land surface areas always wet the evaporation of water will be consistent and thus rain cycle will be regular. It is an easy job for mankind now and is possible only till we have snow on mountains. At the end of holy festival we always had rain (in the evening). Covering of land surface areas by human is reducing the evaporation. We are doing this mistake because we studied rain cycle occurs from the evaporation of water from sea or lakes or rivers. Regular rain means colder weather, snow on mountains, rich vegetation/ balanced ecosystem, recharging ground water and eventually reducing sea water level. Climate change problems are related to water or rain cycle. Without regular rain cycle problems related to water can’t be solved.
Conclusion: Thus it can be concluded that we have climate change because we are studying the process of rain cycle wrong way scientifically. dev.dangol@yahoo.co.uk

dev dongol: 14.10.2011, 07:22

Challenge to IPCC/UNFCCC
Dear Dr. Pachuri and Mr. Algore,
Please give me either one scientific reason/ theory that justifies CC is due to gases OR STOP ACCUSING GASES for CC. Just accusation is not science. CC by gases is impossible. Please visit devbahadurdongol.blogspot.com for solutions to CC and ‘power crisis’. Summary is attached for your convenience. I have also explained the mistake being done in the hydropower engineering and, its correction can give us unlimited hydropower.
Dr. Dev

dev dongol: 25.08.2011, 03:27


dev dongol: 21.08.2011, 18:07

SHAME ON YOU IPCC. Global warming or CC has nothing to do with gases. Gases are actually helping the earth
to cool down by heat transmission principle and convection method of heat transmission. If GW were by GHE
of gases our atmosphere would be warmer as we go higher. TROpOSPHERE, Our climatic atmosphere, IS not layered
it is a homogenous mixture. Heat does not travel from lower to higher temperature but other way. Reflection
is not possible by gases, that’s why they are transparent. So there are no such gases as green house gases.
And, rain cycle has no relation with gases but evaporation, so only with HEAT. We have climate change and
global warming because man has disturbed rain cycle- the natural very effective cooling system. And, that’s
because we have been explaining hydrologic process wrong way. For details please visit my blog:
In the blog I have also explained the mistake done in the hydropower engineering; and correction of
the mistake can give us unlimited hydropower. My email address is dev.dangol@yahoo.co.uk

DougCotton: 07.07.2011, 03:15

There is very serious doubt that the IPCC temperature predictions will come true. This chart shows NASA mean world temperatures up to 1 July 2011 and you can see that the last 12 months was cooler than 2003. http://earth-climate.com/2003-2011.jpg

The real reason that extra CO2 is having no effect is that there is already about three times as much up there than would be needed to capture all the available photons. You cannot create energy. Carbon dioxide is not energy - photons are.

The IPCC based their argument on laboratory tests which had enough photons for the amount of CO2 they had in their test. This was nothing like the real world.

Also, they overlooked obvious cycles in temperatures which can be proven statistically with Fourier transforms. They made their predictions when the 60 year cycle was rising between 1970 and 2000. Now it is starting to fall, though the long-term (934 year cycle) will continue to rise but only by about 0.3 degrees and only until 2059.

I don't care if the majority of scientific opinion is that CO2 raises temperatures. The majority is wrong. CO2 went up linearly whereas temperatures are going down slightly since 2003. The cycles predict that 2059 will be the maximum and then there will be a steady decline for 450 years. We are at a similar point to about the year AD 1077 and heading for a little ice age after the next 60 year mini peak in 2059 (60 years after the 1999 peak which was 60 years after the 1939 peak and 60 years after the 1879-1880 peak etc.

See the new theory at my site http://earth-climate.com

I know you will be reluctant to be branded a denier, but at least recognise the fact that the current temperatures are not rising and ask what's the urgency? Temperatures won't rise until about 2029 and by then the IPCC will have to admit they got it wrong.

This is what will happen to temperatures: http://earth-climate.com/planetcycles.jpg and it is actually based on planet orbits.

measuredata: 13.06.2011, 05:49

Sorry folks, the scare scenarios described here are irrelevant, there are underwater caves all around the world, 10,000 years ago there was 1 mile of ice where my house is. The climate changes all the time, long before we were even here. It has caused extinctions. CO2 is a trace gas, with a minimal effect as a GHG. The proponents of this theory try to use it to scare people, when the numbers on CO2's contribution just don't support alarm. Really they don't, the 30,000+ professionals in the US that signed the oregon petition did so for truth not for money or fame. They did so, as the IPCC has continually pumped out terrifying scenarios of doom due to CO2 from man. So I ask, if CO2 has an almost immeasurable effect, and we have only increase it by 15 out of 380 million in 150 yrs, It has been higher before, and plants actually do better in a high CO2 environment, what could be greener than increasing the life gas of plants? No evidence presented shows a threat, this site is about a political agenda, not scientifically based. Makes me sad to see all the posts that have bought the snake oil, taxing carbon won't reduce it even if it were a threat, wake up people...

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