Flow Through Bering Strait Affects Ice Sheets & Global Climate

A paper was published in the journal Nature Geoscience this week describing an investigation into the influence of the Bering Strait on oceanic circulation between the Pacific, Arctic and Atlantic Oceans.  The investigation found that sea-level fluctuations in the last glacial period were due primarily to changes in Northern Hemispheric ice sheet volumes and not solely to variable solar radiation.  This study (and others in progress) was made possible by more supercomputing resources at NCAR in Boulder, CO.

The relationships between historical ice sheet volume, sea-level height, solar radiation and climatic effects are important to scientists’ efforts to accurately model and interpret model results from ongoing climate research.

The group ran two pairs of experiments: one pair with the North American ice sheets and one pair without.  Within the pairs, all conditions were identical except on had an open Bering Strait and the other a closed Bering Strait.  With an open Bering Strait, relatively fresh water is allowed to circulate from the Pacific Ocean into the Arctic Ocean and then into the Atlantic Ocean – the real world’s conditions for the past 70,000 years or so.

With a closed Bering Strait, that fresh water supply to the Atlantic is largely cut off.  As a result, the overturning current in the Atlantic strengthens, redistributing heat and fresh water on the global scale in different ways.  For instance, northeast North America warms up to 1.5 ^°C annually, while the North Pacific cools up to 1.5 ^°C and a smaller warming occurs over parts of Antarctica.  Precipitation is reduced over most of North America.  As a result, Northern Hemispheric ice sheets melt faster – at a rate of 0.112m per year.  Over millenia, the North American and Greenland ice sheets thin by 560m, increasing global sea-levels by 33m.  It is important to note that these experimental results match up well with observations.

Eventually, the rising sea-levels re-open the Bering Strait circulation.  Pacific waters are then allowed to be transported to the Atlantic, weakening the overturning circulation and shifting heat and fresh water patterns.  This process cools the North Atlantic while precipitation increases over North America.  Cooler temperatures and more precipitation mean more snow lasts throughout the year to rebuild the ice sheet volumes.  Sea levels eventually drop, closing off the Bering Strait and starting the cycle over again.  The model results mesh well with observed ice sheet and sea-level trends observed in nature.

The way in which radiation has been observed (and now modeled) to influence sea-levels and ice sheet volumes does not match well with a simpler case of no Bering Strait influence.  Thus, a prime result of this study indicates that changes in the radiation budget cannot account for climate shifts by itself.  Processes like the Bering Strait’s modulation of climate are indeed very important for climatologists to consider and take into account.  Put another way, the simple way in which climate change deniers view the world have been shown to once again not be sufficient to explain the real world.

I will also note that no mention was made in the paper of future climate scenarios with greatly reduced ice sheet volumes as a result of greenhouse gas pollution.  Logically, one can speculate that deeper seas means more flow through the Bering Strait, leading to weaker circulations, cooler regions of the North Atlantic and more precipitation over North America.  It could eventually act as a modulator on anthropogenic climate change (i.e. cooling a much warmer world), but the time-scales involved (many thousands of years) should be no comfort to policy makers in 2010.  Once again, it is clear that the best way to deal with climate change is to reduce our system forcing.

Cross-posted at SquareState.

Beyond 4 Degrees – Catastrophic Double-Digit Temperature Increases by Mid-Century?

The UK Met Office hosted a conference in last month (Sep 2009) titled, “4 Degrees and Beyond” at Oxford University.  The bottom-line message is confirmation of what many climate activists have been saying for years: there is a much higher potential for much more warming than commonly thought.  The numbers are staggering in their implications, as I’ll detail below.

First, what did these climatologists do?  They ran the IPCC  high emissions scenario (i.e. business as usual (BAU)) in one of the few global climate models capable of analyzing strong carbon cycle feedbacks, a necessary test to truly reveal details of what our current emissions path could bring to the planet.  The reason this test is necessary was apparent in the results: the same warming that resulted from a BAU scenario without the feedbacks by 2099 occurred instead around 2060 in the BAU scenario with the feedbacks.  What implications does that level of warming by 2060 have for the globe by 2099?  Substantially higher temperatures, especially for some regions:

• The Arctic could warm by up to  27.4°F [15.2 °C] for a high-emissions scenario, enhanced by melting of snow and ice causing more of the Sun’s radiation to be absorbed.
• For Africa, the western and southern regions are expected to experience both large warming (up to 18 °F [10 °C]) and drying.
• Some land areas could warm by 12 degrees [7C] or more.
• Rainfall could decrease by 20% or more in some areas, although there is a spread in the magnitude of drying. All computer models indicate reductions in rainfall over western and southern Africa, Central America, the Mediterranean and parts of coastal Australia.
• In other areas, such as India, rainfall could increase by 20% or more. Higher rainfall increases the risk of river flooding.

What Are the Costs of Acting Against Climate Change?

I wanted to collect some information I’ve seen about climate change action costs.  Some of it is right-wing propaganda, some of it is reality-based facts from large-scale studies that have been done.  The short answer is what I’ve been writing for a while: it is far cheaper to act than not to act.

Beginning with the right-wing, extremist, denier propaganda:

On the subject of a still-in-the-works cap-and-trade plan, Con-servatives are running around screaming about a $3,128 tax that would befall the American people.  As usual, they’re trying to work up their base over … nothing.  As usual, they’re misquoting a scientific study by MIT that examined what a potential cap-and-trade plan would do to the “average American”.  As usual, they’re promoting a three-word catch-phrase designed to fool people into buying into their b.s.  They’re calling the cap-and-trade plan a light-switch tax.  What is the true number from the MIT study?  $79 per family (based on 2.56 people, just as the Con-servatives did) in 2015.  The long-term cost to a household?  $215.05.  That’s 6.9% of what the Cons are talking about.  They’ve boosted the number over 14 times its true cost – purposefully lying to generate fear and anger.  As usual, that’s disgusting behavior from the “family-values” crowd.

Reality-based details can be found below.