Global Warming Trends Observed

Revisions to recommended plant-growth regions from 1990 to 2004.

Source: Columbus Dispatch, via Environmental Economics.

Comments

[anne]

http://www.nytimes.com/2007/01/20/world/20climate.html?ex=1326949200&en=9704a8ac0564ad10&ei=5090&partner=rssuserland&emc=rss

January 20, 2007

New Warnings on Climate Change
By ANDREW C. REVKIN

The main international scientific body assessing causes of climate change is closing in on its strongest statement yet linking emissions from burning fossil fuels to rising global temperatures, according to scientists involved in the process.

In fresh drafts of a summary of its next report, the group, the Intergovernmental Panel on Climate Change, has said that it is more than 90 percent likely that global warming since 1950 has been driven mainly by the buildup of carbon dioxide and other heat-trapping greenhouse gases, and that more warming and rising sea levels are on the way.

Some scientists involved in drafting the report confirmed and clarified details but asked not to be identified because it was not finished.

In its last report, published in 2001, the panel concluded that there was a 66 to 90 percent chance that human activities were driving the most recent warming.

The shift in language in the current draft, while subtle, is substantive. If it remains in the final version, scheduled for release in Paris on Feb. 2, it will largely complete a quest that lasted decades to determine if humans are nudging the earth's thermostat in potentially momentous ways.

Drafts of the report project a most likely warming of 4 to 8 degrees if the concentration of carbon dioxide in the atmosphere rises to twice the 280 parts per million that it averaged for many centuries before the Industrial Revolution.

The carbon dioxide concentration is now roughly 380 parts per million, and many climate experts say it will be extremely difficult to avoid hitting levels of 450 or 550 parts per million, or higher, later this century, given growth in populations and fuel use and the lack of nonpolluting alternatives that can be exploited at a sufficient scale to replace fossil fuels....

[Stuart]

And here I thought my wife was just an amazing gardener for getting Calla Lilies (Zone 7+) to winter over in Ohio.

[anne]

http://www.nytimes.com/2007/01/14/weekinreview/14basics.html?ex=1326430800&en=ae92d8885fcf1970&ei=5090&partner=rssuserland&emc=rss

January 14, 2007

Connecting the Global Warming Dots
By ANDREW C. REVKIN

If thought of as a painting, the scientific picture of a growing and potentially calamitous human influence on the climate has moved from being abstract a century ago to impressionistic 30 years ago to pointillist today.

The impact of a buildup of carbon dioxide and other greenhouse gases is now largely undisputed. Almost everyone in the field says the consequences can essentially be reduced to a formula: More CO2 = warmer world = less ice = higher seas. (Throw in a lot of climate shifts and acidifying oceans for good measure.)

But the prognosis — and the proof that people are driving much of the warming — still lacks the sharpness and detail of a modern-day photograph, which makes it hard to get people to change their behavior.

Indeed, the closer one gets to a particular pixel, be it hurricane strength, or the rate at which seas could rise, the harder it is to be precise. So what is the basis for the ever-stronger scientific agreement on the planet's warming even in the face of blurry details?

As in a pointillist painting, the meaning emerges from the broadest view, from the "balance of evidence," as the scientific case is described in the periodic reports issued by an enormous international network of experts: the Intergovernmental Panel on Climate Change, www.ipcc.ch. The main findings of the panel's fourth assessment since 1990 will be released in Paris on Feb. 2.

In the panel's last report, issued in 2001, and in more recent studies reviewed for the coming report, various trends provide clues that human activity, rather than natural phenomena, probably caused most of the recent warming. A number of trends have been identified:

¶The global average minimum nighttime temperature has risen. (This is unlikely to be caused by some variability in the sun, for example, and appears linked to the greenhouse gases that hold in heat radiating from the earth's surface, even after the sun has gone down.)

¶The stratosphere, high above the earth's surface, has cooled, which is an expected outcome of having more heat trapped by the gases closer to the surface, in the troposphere. (Scientists say that variations in the sun's output, for example, would instead cause similar trends in the two atmospheric layers instead of opposite ones.)

¶There has been a parallel warming trend over land and oceans. (In other words, the increase in the amount of heat-trapping asphalt cannot be the only culprit.) ...

[RT]

Holy s**t.

That's all I have to say.

[Ian Whitchurch]

The politics is changing fast here in Australia.

We had some fairly bad bushfires in Victoria - not very bad, but apart from anything else, they took out one of the main power lines to the city of Melbourne, so circa 4 million people got inconvenienced.

The Country Fire Brigade spokesman on national morning television was 100% certain that Global Warming was both real and making fire season worse.

There is a constituency among traditional conservatives for state action to enforce anti-CO2 policies. Hostorically, free marketeers get crunched when traditional conservatives turn on them.

Ian Whitchurch

[James Killus]

There's a general consensus in the climatology community that there is some natural variability in climate. So the last 14 years probably represent some combination of global warming plus the natural variability.

This isn't a good thing, because it makes the overall system less easy to control. For some period of time, during natural cooling periods, global warming from anthropogenic greenhouse gas increases is suppressed. Then you get natural warming plus GG warming, and radical shifts in both climate and public opinion. But then the natural increase shifts back, and GW deniers return.

Add that to the natural delays in effects from feedback mechanisms and climatological "inertia" and you wind up with a situation where the eventual state is much worse than it would be without all the time delays and natural noise.

In other words, we have no idea how much of a problem is already in the pipeline, just a suspicion that it will wind up being worse than anyone really expects, based on the current facts.

Have a nice day.

[anne]

http://www.nytimes.com/2006/06/22/science/22cnd-climate.html?ex=1308628800&en=03c009b6289a6078&ei=5090&partner=rssuserland&emc=rss

June 22, 2006

Science Panel Backs Study on Warming Climate
By ANDREW C. REVKIN

WASHINGTON — A controversial paper asserting that recent warming in the Northern Hemisphere was probably unrivaled for 1,000 years was endorsed today, with a few reservations, by a panel convened by the nation's pre-eminent scientific body.

The panel said that a statistical method used in the 1999 study was not the best and that some uncertainties in the work "have been underestimated," and it particularly challenged the authors' conclusion that the decade of the 1990's was probably the warmest in a millennium.

But in a 155-page report, the 12-member panel convened by the National Academies said "an array of evidence" supported the main thrust of the paper. Disputes over details, it said, reflected the normal intellectual clash that takes place as science tests new approaches to old questions.

The study, led by Michael E. Mann, a climatologist now at Pennsylvania State University, was the first to estimate widespread climate trends by stitching together a grab bag of evidence, including variations in ancient tree rings and temperatures measured in deep holes in the earth.

It has been repeatedly attacked by Republican lawmakers and some business-financed groups as built on cherry-picked data meant to create an alarming view of recent warming and play down past natural warm periods.

At a news conference at the headquarters of the National Academies, several members of the panel reviewing the study said they saw no sign that its authors had intentionally chosen data sets or methods to get a desired result.

"I saw nothing that spoke to me of any manipulation," said one member, Peter Bloomfield, a statistics professor at North Carolina State University. He added that his impression was the study was "an honest attempt to construct a data analysis procedure."

More broadly, the panel examined other recent research comparing the pronounced warming trend over the last several decades with temperature shifts over the last 2,000 years. It expressed high confidence that warming over the last 25 years exceeded any peaks since 1600. And in a news conference here today, three panelists said the current warming was probably, but not certainly, beyond any peaks since the year 900....

[jim]

Could someone tell me what the quantity is that's being graphed here: "average minimum temperature"? I assume a minimum temperature at a place is as cold as it gets there. And some set of minimum temperatures is being averaged. But what set? Is it a moving average? The average across nearby places? The average of January's minimum, February's, March's?

The pictures are impressive. But I'd like to know what's being pictured.

[John Emerson]

Jim: it looks like it's average of the minimum annual temperatures (lowest temperature in any given year) over some rolling number of years.

Where I live has moved from the minus-30-to-40 degrees-Fahrenheit-below-zero zone to the 20-to-30 degrees-below zone. That seems about right.

Global warming is supposed to proceed glacially slowly (ha! ha!) at a degree or two a century, so local results aren't decisive. But it sure does seem weird.

[jim]

John: My guess was actually that it was averaging over nearby reporting stations to try to even out heat island effects, but I hoped someone knew.

The reason for my guess is the DC area is shown in yellow, 0 < AMT < 10. I live in Alexandria, a DC inner suburb. It happens that one of the pipes in my house runs a little too close to a not quite sufficiently insulated wall. Single digit nights I have to worry about it freezing. So I keep an eye out for when the temperature dips below 10. It used to happen with some frequency (which is how I learned of the vulnerability). It's happened like once in the past few years. But localities further from the urban core get colder. So I assumed we were being averaged in with them.

I don't dispute the reality that the charts exemplify. I'm just this anal type that wants to know how they were constructed.

[Esq.]

In the mid-nineties, when I lived on the Massachusetts side of the Mass-VT border, farmers and gardeners said that they planted two or three weeks earlier than they did in the 70s.

The 1990 map linked to shows the Berkshire hilltowns as in the middle of zone 5. IRC, older maps showed zone 4 dipping down almost to Connecticut in the hills. The new map places the border between zones 5 and 6 crossing the hills just south of the VT border.

In other words, using a 1990 revision slights the changes.

[wilsod]

The zone maps confirm what I have done in my garden the last 10 years, inspite of warnings from horticulture scientists. I now enjoy cherries, nectarines, peaches and blackberries that I was foolish to plant. So, in Wisconsin there are some benefits to global warming. In response to a question above, maps at this detail wash out heat islands. Where maps are published in more granular detail, heat islands in deed are displayed.

Wilsod