What are some genuine uncertainties regarding climate change?
It’s widely accepted that human activities are impacting upon the climate and this is supported by reconstructed, observational and empirical evidence. Within the climatic systems there are many inherent complexities and uncertainties. There are known inconsistencies and apparent contradictions and of course, there is much that we don’t fully understand.
What do you consider to be the uncertainties regarding climate change, what are the inconsistencies and in which specific areas do you feel a greater comprehension would be of significant benefit?
Climate sensitivity. Although climate scientists have constrained it pretty well to within 2–4.5°C warming for a doubling of atmospheric CO2, and a most likely value of 3°C, the precise value is still a genuine uncertainty, and important to determine. We’re probably going to reach that 560 ppm CO2 concentration this century (unless we take serious steps to avoid it, which thus far we have not), and knowing whether that means 2°C or 4.5°C or somewhere in between is important.
Feedbacks. Knowing when significant amounts of methane will be released from melting permafrost or the oceans or warming peat bogs, for example. Or when the ocean will become saturated with CO2. Or….
Water vapor. Will relative humidity remain constant, as is assumed in climate models?
Cloudcover. How will different types change in response to a warming world, and will this make cloudcover a net positive or negative feedback?
Adequate Response. How much do we need to reduce anthropogenic CO2 emissions to avoid triggering these feedbacks and causing highly dangerous warming?
Policy Measures. What would be the most effective policy to successfully reduce emissions and atmospheric CO2 (cap and trade, cap and dividend, carbon tax, government regulation, geoengineering etc.)?
I think it’s important to point out a few things.
1) The cause of the current warming is not a significant uncertainty. The IPCC puts the probability that the current warming is dominantly anthropogenic at greater than 90%, and that’s a conservative value. I’d say 99% would be more accurate at this point.
2) Uncertainty can’t be used as justification not to act. For example, for those who want to argue that lower values of climate sensitivity can’t be ruled out (i.e. Lindzen and Spencer), that also means high values can’t be ruled out. It’s just as likely that climate sensitivity to CO2 doubling will be 6°C as it is that it will be 1°C. If you’re arguing for high uncertainty, you’re also arguing that catastrophic results are entirely possible, and therefore that we must act to prevent this possibility.
What causes El Nino.
The degree to which sunspots effect our climate.
The mechanism by which sunspots effect our climate.
As it’s extremely powerful, the fact that we do not understand El Nino means we understand next to nothing about climate change.
As we have obviously expected a sunspot cycle to be in full swing now and we have next to nothing. (today’s sunspot number is 19) we can say we don’t know much.
As we know that temperature on earth correlates very strongly with sunspots, but we don’t know quite how they work, and we don’t know when they’ll peak or disappear, we know very little.
speaking as a non-expert, here’s my list:
Climate sensitivity to primary forcing
Possible effects of rapid decrease in ocean pH (I suspect the ice ages give us no guidance here at all)
How much methane is likely to be involved from the permafrost, or from other reservoirs of methane hydrates, and how large were the impact be?
How much will Arctic melting affect the North Atlantic current (I have an interest in this one; I live in Scotland)? Effects on ocean currents in general. Degree of stratification
I remember reading a paper in Science many years ago (sorry, I don’t have the reference; if anyone here does I hope they will post it) reporting 90% confidence in the reality and seriousness of AGW, but also predicting that the confidence level would remain more or less stuck at 90% for a long time, because of the intrinsic complexities and noisiness of the data
Can CO2 sequestration be made to work, and how confident can we be that it won’t all come pharting up again in a few thousand years and trigger disaster?
Whether we have the foresight and political will to enact changes that will mainly benefit people whom we don’t know and who are not yet born.
And all the things mentioned by Dana and Paul.
the projected areas where drought and flooding may occur-it will be hard to grow crops in areas currently used…………………
I only have one question. How bad is it going to get? Are we going to be at the optimistic end of the IPCC projections or the crappy end?
"Good" is bad and "bad" is apocalyptic.
I think even the most environmentally aware among us are cavalier about the chance of things getting really bad, and don’t understand the magnitude of change necessary to avoid a train wreck.
http://fora.tv/2009/08/18/A_REALLY_Inconvenient_Truth_Dan_Miller
Global warming doesn’t exist. It was revealed that the University that originally did the research had altered their results and so there really isn’t a problem at all.
It’s kind of funny, the movie An Inconvenient Truth had so many false facts that it was banned in parts of Europe!
Although it is accepted fact that man is polluting the planet, NOONE KNOWS OR CAN ACCURATELY MEASURE THE EFFECTS this is having on the climate. Scientists can (and have) manipulate(d) data to fit any "truth" they choose, and for every supposed "proven fact", there is another that disproves it. This holds true for the reasons behind unpredictable weather patterns, the supposed rise in ocean levels and the supposed melting of icebergs.
The fact is; Earth goes through different climate cycles, and has done so for millions of years., and will continue to do so.
And, once mankind has died out (maybe faster because of all the stupid things we do to our beautiful planet), it will still be here long after we’re not.
I really do wish mankind (and esp. big business /oil) would treat the Earth with more respect and do more to stop pollution, and also stop things like over fishing and poaching, and to encourage conservation. However, I also believe that global warming is a myth. And, while we’re on the subject; the whole ‘carbon credit’ scheme is a absolute joke, totally open to misuse and corruption.
Money and greed is the root of all evil, and it will be our demise!