Will Work To Clean Up Everglades Matter?

Back in 2000, the Comprehensive Everglades  Restoration Plan was initiated by the Army Corps of Engineers.   Consisting of over 50 major projects to bring the Everglades back from the brink, the program has thus far mostly been a success.  It’s cost more than originally planned, but measurable progress has been made.

My question is, how much is the multi-billion dollar project worth to Floridians and Americans?  What I mean by that is, within a few decades, the Everglades will be sitting at the bottom of the Atlantic Ocean if nothing is done to slow down global warming.  Will those billions be wasted in trying to save the Everglades from fresh water flow problems while sea levels continue to rise?  How many more billions would Americans be willing to spend to build and maintain infrastructure to keep the sea water out of the Everglades?

We can continue rumbling down the dangerous path we’re on and refuse to take the threat of global warming seriously or we can choose to acknowledge the reality we’re facing and do something about it now, while we still can.

21st Century Sea-Level Rise: More Than IPCC 4AR Projected

New research was published a few months ago that provides additional evidence that sea-level projections made by the IPCC’s 4th Assessment Report are likely too conservative: sea-levels are more likely to be 1 meter higher than they were in 1990 (Vermeer and Rahmstorf), rather than only 0.5m higher, as projected by the IPCCs multi-model ensembles.

There was nothing inherently bad about the IPCC’s 4AR; I and others simply feel that their final report had to include more conservative estimates and projections in order for world governments to sign off on its language.  That does the world’s citizens an injustice, however.  In order to correctly assess risk, people need best- and worst-case scenarios available to them.  The most likely amount of sea-level rise by 2100 provided by the 4AR came out to between 0.2m and 0.6m.  Those estimates have implications to world societies, conservative though they were.  Additional implications will enter into our lives if there is 0.4-0.8m additional rise.

I want to stay on the IPCC projections for another moment.  The 2007 estimates included rates of sea level rise between 1980 to 1999 and 2090 to 2099 in metes and mm/yr.  The mm/yr rates in particular interest me because they allow for both the IPCC projections and the updated projections from the Vermeer and Rahmstorf paper to be placed in context with actual observations.  The six emissions scenarios examined by the IPCC had rates of 1.5, 2.1, 2.1, 1.7, 3.0 and 3.0mm/yr.  Satellite observations indicate that there has been approximately a +3.2mm/yr change in sea level (linear fit since 1993).  Only two IPCC emissions scenarios are close to the observed rate, and both of them underestimate them, albeit very slightly.  It is worth pointing out that the IPCC wrote:

The global average sea level rose at an average rate of 1.8 [1.3 to 2.3] mm per year over 1961-2003.

Averages over longer periods of time like this will, by nature of the averaging, tend to reduce extreme values that are small in number, as in the case of sea-level rise in the past 10 years or so.

Onto the new research findings.  Vermeer and Rahmstorf developed and tested an updated methodology to project future sea levels based on projected changes in temperature that was originally presented by Rahmstorf in a separate paper.  The original technique was based on the assumption that the sea level response time scale was long compared to the time scale of interest.  The updated technique allows for some sea level components to change quickly to a given temperature change.  The updated technique is shown to agree very well with historical data (82% of sea-level rate variance from the year 1000 to 2000).

Applying the technique to future conditions provides another potential case against which real-world observations can be compared.  By the year 2100, three different IPCC emissions scenarios generate a range of sea level projections: 1.0m, 1.2m and 1.4m, as the figure below (from the paper) shows.  That’s a big difference between the AR4 projections, using the same emissions scenarios, of 0.2-0.4m.  That extra potential meter of sea level rise will indeed have large implications across the world.

The figure shows the possible range of sea level rise values for 3 emissions scenarios considered by the IPCC: B1 in green, A2 in blue and A1F1 in yellow.  The observed emissions to date is represented by the red curve.  One important detail to note is our actual emissions rate is currently at the high end of all those considered by the IPCC (Copenhagen Diagnosis Figure 1, after Le Quere et al. 2009).

The IPCC projected a higher future rate of sea-level rise than was observed from 1961-2003.  1.8mm/yr equals 0.18m after a century (by linear extrapolation), slightly below the 0.2 minimum projected by all emissions scenarios.  Recent observations of 3.2mm/yr equals 0.32m after a century – well within the IPCC range, but well below the Vermeer and Rahmstorf range.  So what will it take to get 1.0-1.4m of sea level rise by 2100?  10mm-14mm/yr or 3-4X as much per year as is currently being observed.  There are some important details involved with that projection.  First of all, sea level change is not linear.  It varies year to year and decade to decade.  There has to be a transition from today’s 3.2mm/yr to the 10mm/yr necessary to achieve 1m sea level rise by 2100.  The rate of sea level rise would therefore have to increase over time.

Given the state of today’s atmosphere, oceans and cryosphere, a drastic change would have to occur for sea levels to rise by 10mm+ per year by the end of this century.  It is widely known that the IPCC’s science basis did not include a number of processes and feedbacks to the globes’ continental ice sheets, glaciers and sea ice (cryosphere).  Again, that wasn’t their fault – it just happens to be a weak link in the climate community’s research.  Work has been conducted since the IPCC 4AR to rectify those shortcomings.  Much more work will have to be done in the future.  Once that area is fleshed out further, I expect the IPCC’s projections to be more closely aligned with the leading research of today.

h/t RealClimate

http://sealevel.colorado.edu/

Rising Sea Levels: Disappearing Islands & Underestimation

Word came yesterday of an island in the Bay of Bengal that has quietly slipped beneath rising seas.  New Moore Island was a rocky island that was 2 miles long and 1.5 miles wide.  This isn’t the first island to succumb to rising sea levels, nor will it be the last, especially since we continue to belch greenhouse gas pollution into the atmosphere.  Indeed, 10 additional islands in the same area continue to face submersion in the near future.  This news isn’t a surprise to any reputable scientist who has studied climate change, nor to any activist who has followed the state of the science.

Also unsurprisingly, Sen. James Inhofe’s family was not photographed on New Moore Island constructing a building in further efforts to misinform the fringe anti-science crowd.  I’m sure the lunatic Senator would cite his favorite conspiracy of global economic domination as the real topic to be discussed.  It wasn’t his island that disappeared, after all.  You’ll also note that the disappearing islands don’t garner much corporate media attention.  Since the stenographers look for controversy, there must be a lack of dimwits who are willing to go record disputing these events.

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.