June 02, 2007
Global Warming To Increase Rains?

Will rise in atmospheric carbon dioxide (CO2) and consequent warming cause massive droughts and famine? Maybe not.

What goes up, must come down. This basic rule of gravity on Earth's surface also applies to water vapor in the atmosphere. And as the air, earth and sea warms with climate change the atmospheric water vapor load increases by as much as 6.5 percent per degree Celsius, according to satellite data from the past 20 years. As the water vapor increases, so, too, will rainfall, argues physicist Frank Wentz, director of Remote Sensing Systems (RSS) in Santa Rosa, Calif., a provider of climate data records contracted by NASA.

While global climate models predict less wind due to global warming Wentz and colleagues found that surface winds increased with recent warming. Winds will blow evaporated water from the oceans over land and hence winds create the potential for increased precipitation if the planet warms further.

But climate models project that global warming will also bring weaker winds, leading to less water evaporating from the ocean and counteracting the effect of warming. Models predict that worldwide precipitation — which must match the amount of evaporation — will increase by only 1-3% for each degree of future global warming.


They report in Science that the amount of water in the atmosphere, evaporation and precipitation all increased at the same rate, by about 1.3% per decade1 — or about 6.5% for every degree of warming. Surface winds increased, not decreased, with warming.

Why is this important: The "Apocalypse Soon" global warming doomsters predict global warming will lead to reduced precipitation and therefore crop failures and massive hunger. The official view of all Correct Thinking people is that global warming means massive droughts.

In February, the Intergovernmental Panel on Climate Change (IPCC) cited studies showing "extreme drought increasing from 1% of present-day land area to 30% by the end of the century."

The new study suggests models are flawed, underestimating how increased humidity in a warmer climate produces more rain clouds, Wentz said by e-mail.

Some climatologists are skeptical of these results.

Gavin Schmidt, a climatologist at the NASA Goddard Institute points out that the 20 years studied were dominated by a couple of El Niño events, which increased precipitation during that time. "The trends are not really significant," he says. "I think some more work would be necessary to really pin their argument down."

But if the warming brings more rain then more land might become usable for crops - especially lands closer to the north and south poles. Areas closer to the poles will gain longer growing seasons as nights get warmer in fall and spring and frost stops sooner and starts later. Massive farms in Siberia, Alaska, and northern Canada anyone?

Of course, that doesn't mean that a large increase in world temperatures will deliver net benefits. If Antarctica mostly melts then land areas will shrink due to rising ocean levels. Though we could build dikes to hold back the water ala Holland. Not sure that is feasible for Florida though. A cheaper solution for that problem: cool the poles with climate engineering to keep all the snow and ice frozen.

What worries me most about rising atmospheric CO2: Acidification of the ocean. That seems like a much tougher problem to prevent. Any ideas on that?

Share |      Randall Parker, 2007 June 02 07:26 PM  Climate Trends

Steven Ashley said at June 2, 2007 7:43 PM:

Finally, a study that agrees with what I learned in High School Science Class. Warmer air holds more water vapor than Cold air. Warmer Temperatures means more water vapor, more water vapor means more rain.

And here is another from High School Science Class, the Earth has been warming on average since the last Ice Age, as has the other planets in the solar system, and I don't see how humans had a lot to do with the thaw.

I don't think anyone knows the optimal temperature for human life but I doubt we are at it right now.

Darryl Mathews said at June 3, 2007 7:43 AM:

The "optimal temperature" for the earth is irrelevant. Climate always, always changes. There is always either cooling or warming, often both at the same time in different regions.

The problem comes when corrupt schemes like carbon trading try to reap huge robber baron profits from the public's gullibility. But the IPCC is under the jurisdiction of the UN, and how can the UN be corrupt? How, indeed.

Bob Badour said at June 3, 2007 8:58 AM:

I can think of no clearer evidence of the moral and intellectual bankruptcy of the global warming scaremongers.

Higher temperatures means more kinetic energy which necessarily means more wind. Higher temperatures means more evaporation which necessarily means more clouds and more precipitation.

Kurt9 said at June 3, 2007 10:53 AM:

Increased atmospheric temperatures increases the amount of energy in the air. This, in turn, increases the amount of evaporation from the oceans which, in turn, will increase the amount of rainfall in most places. This will be largely beneficial for most of the world.

I have always believed that global warming, if real, would be beneficial to us.

Julie said at June 3, 2007 2:03 PM:

Water vapor, as I recall from my high school physics, is THE major
greenhouse gas, tho who'd know it these days. So don't go applauding
so fast.

Wanna know my real nightmare scenario? The top scientists/politicos
know that the warming is caused by the sun -- and know that nothing we do can stop a run away warming of thesun. So they cooked up the CO2 scenario to suggest to the mob that we CAN DO Somthing. That way, the billions of people don't riot in the streets, invent weird new religions, go berserk, etc. Instead, they engage in fruitless activities, but keep busy.

Randall Parker said at June 3, 2007 2:14 PM:


If the global warming is caused by an increase in solar output we could easily cool the poles with climate engineering. For $1 billion per year we could make the planet very cold.

For a much larger but still affordable sum of money we could place satellites in orbit that would block out much larger amounts of sunlight.

Alternatively, we could put up satellites that would reflect more light toward the Earth. We could even light up the night time.

Randall Parker said at June 3, 2007 7:19 PM:

I deleted 2 posts by David Mathews and one by Bob Badour because the lack of constructive content and, in David's case, the long length of his lack of content. If you want to know what David Mathews said read other posts he's made on other threads. He always says (and only says) that humanity is flawed, evil, a plague on other species, and therefore doomed to extinction. But he doesn't even say it in an interesting way - let alone with brevity.

momochan said at June 4, 2007 1:40 PM:

The "optimal temperature" for the earth is irrelevant. Climate always, always changes. There is always either cooling or warming, often both at the same time in different regions.

Asteroid strikes are also natural, and apparently not as uncommon as we might wish. Would you be quite so hands-off if we were aware of a 1 km chunk of rock with, say,a 5% chance of hitting the planet?

This, in turn, increases the amount of evaporation from the oceans which, in turn, will increase the amount of rainfall in most places. This will be largely beneficial for most of the world.

Increased heat will also increase moisture evaporation from the soil. Can you demonstrate how drier soils, or wide swings in soil moisture in a given location, will be beneficial? And how can torrential rains -- that is, increased precipitation during a relatively short period of time -- be beneficial? I thought farmers wanted gentle rain.

Paul Dietz said at June 5, 2007 6:12 AM:

I recently saw another interesting advance in climate science, dealing with understanding of vertical mixing in the oceans.

The oceans transport heat from the tropics to the poles by a mechanism involving sinking of cold, dense water near the poles and upwelling of the cooler water in the tropics. The former has been better understood than the latter. Models have typically used an average upwelling scheme, where the upwelling is spread over the tropical oceans. This had been known to fail to adequately model El Nino events.

Now, researchers have found tropical cyclones cause upwelling. As a result, increased cyclone frequency/intensity may act as a thermostat, moderating temperature increases at low latitudes. This is both good and bad news. Good, in that temperature increases in the already hottest areas could have severe health impacts. Bad, in that it doesn't really affect polar warming (where ice will be melting) and because increased storms will themselves cause damage.

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