Monday, July 18, 2011
Think it's hot now? Just wait a few years!
Forty states this week will see high temperatures 90 or above. Many places (such as Oklahoma City) will see their 17th day or more of temperatures over 100. Other parts of the nation are seeing a combination of high temperatures with humidity producing "feels like" temperatures of 100 or above (it was 113 in Minneapolis only a few days ago by this heat index).
Many people want to believe this is just an aberration, an unusually hot but annoying period in one ultra hot summer, but I have news for them: it's just the beginning of ever escalating and intense heat waves which will also see "cool" temperatures at night barely different from daytime highs. Get braced for an accelerated period of global warming! Welcome to the pre-runaway greenhouse effect phase!
Oh, for sure, the meteorologists will point to large high pressure domes over the nation's midsection and expatiate on that and how long it may last. The impression given here is of a transitory meteorological phenomenon which has little or no connection to climate science. So we just need to expect in coming years that the jet stream will float high over Canada and monster Highs (high pressure areas, with a capital H) will sit over the U.S. and other places and make conditions unbearably hot by keeping the jet stream away and hot air flooding in from the south.
But these guys never touch on the whys and wherefores! Well, Geophysicist and climate scientist S. George Philander did more than ten years ago in a small but hot-button piece in Eos: Transactions of the American Geophysical Union (March 31, 1998):‘Who is El Nino?’
Philander argued that El Nino and its sister cycle 'La Nina' are not merely the yin and yangs of a meterological cycle (La Nina ended in May, giving rise to an especially fierce El Nino) but actually offshoots of climate change in terms of their expected future behavior. Thus, as more CO2 is pumped into the atmosphere (as indicated by the Keeling curve - which shows CO2 injection has exceeded the absorption capacity of the oceans), El Nino will ramp up leading to blistering hot and dry conditions, even as La Nina continues her antics bringing cooler spells and precip. However, unmentioned is the game changer of altered albedo.
To grasp this, try to think of what happens when you open the door of your fridge and allow it to defrost. Over a rather brief time interval all your ice melts (de-frosting) and the fridge if left will reach thermal erquilibrium with the room temperature. At this point no ice remains at all. In a similar way, the Arctic is defrosting (and to a lesser extent the Antarctic) and this is encapsulated in the lower diagram.
The defrosting of the Arctic arises from the melting of its polar ice and sea ice, as well as large glaciers and that includes much of the land mass of Greenland. The situation worsens as temperatures (from higher CO2 levels) lead to earlier and earlier melting, analogous to leaving the fridge door open longer and longer. Surface temperatures last summer ranged up to 3 Celsius higher than average and generated a much earlier melting.
When snow melts, grains tend to cluster in a process called 'constructive metamorphism. This reduces the albedo or reflectivity of the surface - leading to increased absorption of solar radiation. Meanwhile, bare ice is much less reflective than snow, absorbing even more solar radiation and further speeding any melting. (In the diagram, the red arrows indicate incoming radiation and the blue arrows indicate radiation reflected back into space. Percentages give the amounts of reflected incoming solar radiation).
As anyone can see (even without a physics background)the above process over time results in ever diminished reflection of solar radiation back into space, a darker Earth surface - with more IR (infrared radiation)absorbed - which reinforces more melting, which in turn leads to more absorbed solar radiation and ever more melting - in a positive feedback loop that will become ever more consolidated.
As it does so, the effects will not be unlike allowing a massive 'defrosting' of the Arctic and a coalescence of the cooler air toward ever more northerly latitudes, while southerly regions (or even temperate one) see hot air trapped almost in perpetuity. (In the sci-fi novel, Heat, one of the best written, at the extreme of global warming depicted, massive highs sat over the midsection of the U.S. for MONTHS without moving as temperatures regularly hit 110-120 each day and barely went down to 95-100 at night - pushing all energy systems to the brink and beyond(including all major power grids, driven into shutdowns by overuse of a/c).
Also, in 'Heat', monster infernos erupted across the country ravaging tens of thousands of square miles not just tens of thousands of acres. By this stage, the runaway greenhouse effect was approaching.
Why has the heat ramped up to such an extent? As noted, the increasing infusion of CO2 is one reason, and the Keeling curve shows ultimately a 'tipping point' will be reached if we refuse to control CO2 output. That tipping point is conjectured to be in the vicinity of 500-560 ppm of CO2 concentration. It's a tipping point because once reached, we'll not only have to worry about the manmade catastrophe (from the CO2 arising from fossil fuel burning) but from the CO2 that will begin to be "out-gassed" from the planet's immense store of carbonate rocks (which will join all the methane outgassed from melting Arctic permafrost). One climate scientist I know has described it as "the ultimate climate-change clusterfuck and we'll be right in the middle of it".
In an article appearing in Eos (Vol. 83, No. 34), from August 20, 2002, ‘Progress Made in Study of Ocean’s Calcium Carbonate Budget’, the author notes that sedimentary carbonates represent the largest reservoir of carbon on Earth. The author also noted that “a third of the anthropogenic CO2 that has been added to the atmosphere since the middle of the 18th century has been absorbed by the oceans". This means that the oceans, acting as CO2 reservoirs, have actually masked the worst effects of global warming. The trouble there is that Keeling's curve discloses they're no longer holding the line, since CO2 injection is now exceeding the oceanic uptake rate!
Increases of atmospheric CO2 also increase concentrations of inorganic carbon, mainly in the forms pCO2 and HCO3 in the oceans. A side effect is to also diminish the pH of sea water. No surprise then that the oceans' measured acidity is now nearly 30% higher than at the beginning of the Industrial Revolution. Some projections show at the currently increased rate of acidification no sea life (including phyto-plankton) will be around within 15 years. That, of course, implies total collapse of all ocean food chains!
The other factor that's enabled a more rapid heating from global warming, is the reduction of global dimming. The effect was first spotted by Gerry Stanhill, an English scientist working in Israel. Stanhill called the phenomenon 'global dimming', but his research, published in 2001, met with a skeptical response from other climate scientists. It wasn't until several years later that 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.
Dimming appears to be caused by air pollution. 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, enhancing albedo and hence offsetting the lowered albedo from Arctic melting.
Stanhill and others estimated that global dimming masked up to one third of global warming for the past fifteen or so years. However, the global dimming effect has markedly receded, largely owing to new and improved cleaner air standards. This means the one-third of global warming formerly masked will not be masked any more - and we are now seeing the effects of that!