America,
I don't buy this, at all. Sorry.
Yes, the world has been warmer. Yes, glaciers have been much less in abundance. Yes, oceans have been much higher. Etc., etc.
None of this means these are directions we want to head. Nor does it say there isn't an historically unique rate of change in evidence today. Nor does it say humans aren't having a pervasive impact that contributes strongly to both the sign (+ or -) and the magnitude of recent rates.
You simply are placing yourself against what the current state of science theory and result says. And that's not a very smart place to put yourself unless you are in a position to claim a comprehensive exposure to it. The scientists active in these areas make it their business.
You've done nothing to convince me that you are in a better position to be able to say "this is quite normal," Joerg. It may sting a little to realize that I would take their word over yours. But in this case, I do. It's as basic as that.
Here's some quotes from last week's report:
"Has global warming recently slowed down or paused?
"No. There is no indication in the data of a slowdown or pause in the human-caused climatic warming trend. The observed global temperature changes are entirely consistent with the climatic warming trend of ~0.2 °C per decade predicted by IPCC, plus superimposed short-term variability (see Figure 4). The latter has always been ? and will always be ? present in the climate system. Most of these short-term variations are due to internal oscillations like El Niño ? Southern Oscillation, solar variability (predominantly the 11-year Schwabe cycle) and volcanic eruptions (which, like Pinatubo in 1991, can cause a cooling lasting a few years).
"If one looks at periods of ten years or shorter, such short-term variations can more than outweigh the anthropogenic global warming trend. For example, El Niño events typically come with global-mean temperature changes of up to 0.2 °C over a few years, and the solar cycle with warming or cooling of 0.1 °C over five years (Lean and Rind
2008). However, neither El Niño, nor solar activity or volcanic eruptions make a significant contribution to longer-term climate trends. For good reason the IPCC has chosen 25 years as the shortest trend line they show in the global temperature records, and over this time period the observed trend agrees very well with the expected anthropogenic warming."Nevertheless global cooling has not occurred even over the past ten years, contrary to claims promoted by lobby groups and picked up in some media. In the NASA global temperature data, the past ten 10-year trends (i.e. 1990-1999, 1991-2000 and so on) have all been between
0.17 and 0.34 °C warming per decade, close to or above the expected anthropogenic trend, with the most recent one (1999-2008) equal to 0.19 °C per decade. The Hadley Center data most recently show smaller warming trends (0.11 °C per decade for 1999-2008) primarily due to the fact that this data set is not fully global but leaves out the Arctic, which has warmed particularly strongly in recent years."It is perhaps noteworthy that despite the extremely low brightness of the sun over the past three years (see next page); temperature records have been broken during this time (see NOAA, State of the Climate,
2009). For example, March 2008 saw the warmest global land temperature of any March ever measured in the instrumental record. June and August 2009 saw the warmest land and ocean temperatures in the Southern Hemisphere ever recorded for those months. The global ocean surface temperatures in 2009 broke all previous records for three consecutive months: June, July and August. The years 2007, 2008 and 2009 had the lowest summer Arctic sea ice cover ever recorded, and in 2008 for the first time in living memory the Northwest Passage and the Northeast Passage were simultaneously ice-free. This feat was repeated in 2009. Every single year of this century (2001-2008) has been among the top ten warmest years since instrumental records began."...
"Can solar activity or other natural processes explain global warming?
"No. The incoming solar radiation has been almost constant over the past 50 years, apart from the well-known 11-year solar cycle (Figure
5). In fact it has slightly decreased over this period. In addition, over the past three years the brightness of the sun has reached an all-time low since the beginning of satellite measurements in the 1970s (Lockwood and Fröhlich 2007, 2008). But this natural cooling effect was more than a factor of ten smaller than the effect of increasing greenhouse gases, so it has not noticeably slowed down global warming. Also, winters are warming more rapidly than summers, and overnight minimum temperatures have warmed more rapidly than the daytime maxima ? exactly the opposite of what would be the case if the sun were causing the warming."Other natural factors, like volcanic eruptions or El Niño events, have only caused short-term temperature variations over time spans of a few years, but cannot explain any longer-term climatic trends (e.g., Lean and Rind 2008)."
"...
"Isn?t climate always changing, even without human interference?
"Of course. But past climate changes are no cause for complacency; indeed, they tell us that the Earth?s climate is very sensitive to changes in forcing. Two main conclusions can be drawn from climate history:
Climate has always responded strongly if the radiation balance of the Earth was disturbed. That suggests the same will happen again, now that humans are altering the radiation balance by increasing greenhouse gas concentrations. In fact, data from climate changes in the Earth?s history have been used to quantify how strongly a given change in the radiation balance alters the global temperature (i.e., to determine the climate sensitivity). The data confirm that our climate system is as sensitive as our climate models suggest, perhaps even more so.
"Impacts of past climate changes have been severe. The last great Ice Age, when it was globally 4-7 °C colder than now, completely transformed the Earth?s surface and its ecosystems, and sea level was
120 meters lower. When the Earth last was 2-3 °C warmer than now, during the Pliocene 3 million years ago, sea level was 25-35 meters higher due to the smaller ice sheets present in the warmer climate."Despite the large natural climate changes, the recent global warming does stick out already. Climate reconstructions suggest that over the past two millennia, global temperature has never changed by more than
0.5 °C in a century (e.g. Mann et al. 2008; and references therein)."
hehe. Well, I wasted my time already. So there.
Of course that's an important question. It's been answered, to a sufficient degree to be useful.
In other words, you don't want to spend the time needed to gain a comprehensive view. I can accept that. But realize what it means as far as my taking your opinion on any of this.
My feeling here is that climate science is huge. Really huge. No one masters all of it. But if you can't even be bothered to take a point you are making -- not something someone else decides to say or write, but something you decide on your own is true enough that you are willing to place yourself in a position of making claims about it -- and follow through with even that single thing long enough to find out where it takes you when you gain a fuller view of even that tiny corner of things....
Well, why should I care, then?
Yeah. It takes work. So what? Spend it, or don't. But if you don't, even in cases where you feel comfortable talking strongly about it... then it undermines (to me) what you say. You either care about your opinion or you don't. And if you don't, why should I? (On this subject, obviously. On many others, I'm all ears.)
Jon