Really interesting report on why global warming is affecting sunlight levels

[shamrock_uk]

Really good article which also explains one of the 'inconsistencies' often cited by those dismissive of the current evidence for the effects of pollution.

Why the Sun seems to be 'dimming' By David Sington We are all seeing rather less of the Sun, according to scientists who have been looking at five decades of sunlight measurements. They have reached the disturbing conclusion that the amount of solar energy reaching the Earth's surface has been gradually falling. Paradoxically, the decline in sunlight may mean that global warming is a far greater threat to society than previously thought. The effect was first spotted by Gerry Stanhill, an English scientist working in Israel. Cloud changes Comparing Israeli sunlight records from the 1950s with current ones, Dr Stanhill was astonished to find a large fall in solar radiation. "There was a staggering 22% drop in the sunlight, and that really amazed me." Intrigued, he searched records from all around the world, and found the same story almost everywhere he looked. Sunlight was falling by 10% over the USA, nearly 30% in parts of the former Soviet Union, and even by 16% in parts of the British Isles. Although the effect varied greatly from place to place, overall the decline amounted to one to two per cent globally every decade between the 1950s and the 1990s. Dr Stanhill called it "global dimming", but his research, published in 2001, met a sceptical response from other scientists. It was only recently, when his conclusions were confirmed by Australian scientists using a completely different method to estimate solar radiation, that climate scientists at last woke up to the reality of global dimming. quote: My main concern is global dimming is also having a detrimental impact on the Asian monsoon ... We are talking about billions of people Professor Veerhabhadran Ramanathan

Dimming appears to be caused by air pollution.

Burning coal, oil and wood, whether in cars, power stations or cooking fires, produces not only invisible carbon dioxide - the principal greenhouse gas responsible for global warming - but also tiny airborne particles of soot, ash, sulphur compounds and other pollutants.

This visible air pollution reflects sunlight back into space, preventing it reaching the surface. But the pollution also changes the optical properties of clouds.

Because the particles seed the formation of water droplets, polluted clouds contain a larger number of droplets than unpolluted clouds.

Recent research shows that this makes them more reflective than they would otherwise be, again reflecting the Sun's rays back into space.

Scientists are now worried that dimming, by shielding the oceans from the full power of the Sun, may be disrupting the pattern of the world's rainfall.

There are suggestions that dimming was behind the droughts in sub-Saharan Africa which claimed hundreds of thousands of lives in the 1970s and 80s.

There are disturbing hints the same thing may be happening today in Asia, home to half the world's population.

"My main concern is global dimming is also having a detrimental impact on the Asian monsoon," says Professor Veerhabhadran Ramanathan, professor of climate and atmospheric sciences at the University of California, San Diego. "We are talking about billions of people."

Alarming energy

But perhaps the most alarming aspect of global dimming is that it may have led scientists to underestimate the true power of the greenhouse effect.

They know how much extra energy is being trapped in the Earth's atmosphere by the extra carbon dioxide we have placed there.

What has been surprising is that this extra energy has so far resulted in a temperature rise of just 0.6 degree Celsius.

This has led many scientists to conclude that the present-day climate is less sensitive to the effects of carbon dioxide than it was, say, during the ice age, when a similar rise in CO2 led to a temperature rise of six degrees Celsius.

But it now appears the warming from greenhouse gases has been offset by a strong cooling effect from dimming - in effect two of our pollutants have been cancelling each other out.

This means that the climate may in fact be more sensitive to the greenhouse effect than previously thought.

If so, then this is bad news, according to Dr Peter Cox, one of the world's leading climate modellers.

As things stand, CO2 levels are projected to rise strongly over coming decades, whereas there are encouraging signs that particle pollution is at last being brought under control.

"We're going to be in a situation unless we act where the cooling pollutant is dropping off while the warming pollutant is going up.

"That means we'll get reducing cooling and increased heating at the same time and that's a problem for us," says Dr Cox.

Even the most pessimistic forecasts of global warming may now have to be drastically revised upwards.

That means a temperature rise of 10 degrees Celsius by 2100 could be on the cards, giving the UK a climate like that of North Africa, and rendering many parts of the world uninhabitable.

That is unless we act urgently to curb our emissions of greenhouse gases.

You can see more on this report on Thursday's Horizon, BBC Two, at 9.00pm GMT.
Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/h...re/4171591.stm

Published: 2005/01/13 14:10:30 GMT

© BBC MMV[/QUOTE]

Nice article, Shamrock. That's a pretty disturbing bit of information, even moreso if it's met with the same ignorant derision that the global warming / pollution problem has been facing in the last few years.

[Azred]

Has anyone done any studies on what the increased levels of atmospheric carbon dioxide are doing to oceanic algae growth rates?

My biggest complaint against environmental scienctists is that so many of them are always pessimistic about every statistic and that some of this pessimism is designed to grab headlines. They make it sound as if a vast majority of the population will be dead by 2100, but a more realistic prediction is that we will deal with whatever happens and adjust accordingly. Even if the average global temperature rises 10C by then, then that means vast portions of Antarctica will be free of ice and ready for habitation, so people who had to leave equitorial regions could settle there.

Science is about presenting facts. Predictions are mathematical models and climate models are fundamentally weather models, thus susecptible to the impossible-to-predict effects of chaos.

[shamrock_uk]

Yes, I think you're right Azred - it does seem like scaremongering is a tactic used to grab headlines and it only serves to increase scepticism. Of course, if they're all telling the truth we're a bit screwed

I believe we'll adapt as well, and it ties in neatly with an article I read recently titled 'Tsunami's don't kill people, Poverty does' which basically tried to show how the casualties in a country like America would have been much much smaller due to technology, decent infrastructure etc etc. I'll see if I can find it online later.

That's one of the particular strengths of the evidence this article presents - solar radiation is something that can be measured and quantified unequivocally and is therefore much more 'concrete' than the evidence presented for global warming. Also, the fact that a noticeable change has occurred within such a (relatively) short time period eliminates all the usual guesswork about whether its part of a much longer climate change that's natural.

[Lucern]

There is a lot to be pessimistic about in terms of ecological/environmental sciences, and little grounds for optimism that we'll 'adapt' in relatively short time imo. Really, every macrobiology class I've had is quite depressing. Still there is some optimism. If there wasn't then nobody would bother trying to figure out how to restore a blackland prairie or how to take wood from a rainforest in a way that'll grow back.

I do, however, like the idea that we'd get our acts together and not treat everyone who says that something might be wrong with our environment as an alarmist. Yes, sometimes they are alarmist (and amplified in reporting), and we've only had the wherewithal to study the environment relatively recently, but there are serious problems that can only point to human activity. It helps to read the actual research rather than the report on the research. At some point the critical eye, mine at least, turns on the sources and kinds of resistance to such ideas. What's it going to take to convince some that we can change our environment for the worse?* I see an unnecessarily politicized version of science that gets bantered around past the actual research. Pick a less politicized topic like mass extinction for a clearer assessment of an environmental problem. I would like to see us take steps towards avoiding rather than dealing with large scale problems when it's too late to 'fix' them.

The first follow-up study to this one should be to see if there is a discernable change in autotrophic life (anything that produces its own energy, including algae) by the change in sunlight. There should be, assuming the validity of these studies, but the more important question is how they might have changed. It would give us a clue about how to deal with what has changed thus far and in the event of further change.

*Not directed at anyone here, but I've encountered people who believe this. Members of my family believe it. Check out Rush Limbaugh's "See, I told you so." for a short dismissive discussion on the matter. One aspect of the scientific debate seems to be about whether the glass is half empty or half full, but the very politicized version seems to be about whether problems actually exist at all. Scientific skepticism is primary to what science is, but we should remain skeptical of the agendas of advocates and skeptics.

[John D Harris]

Sounds like what we need is more "tiny airborne particles of soot, ash, sulphur compounds and other pollutants." producing forms of energy to combat the .06% increase from CO2.