Did Arctic Sea Ice Respond Almost Immediately to Human-Caused Temperature Change?

In 2004, a scientific study analyzing driftwood freed by Arctic melt determined that sea ice in the coldest regions of the Arctic was at the lowest level in 3,000 years. Since that time, Arctic sea ice has continued to rapidly decline. Then, in 2013, another study of ice cores released just this month found that global temperatures are now as hot as they were 3,000 years ago.

The results of these two studies begs the question: did Arctic sea ice respond almost immediately to human caused temperature change?

The answer to this question is an important one because much of the assertion that human caused climate change will be gradual rests on the assumption that things like vast ice sheets only slowly respond due to the inertia inherent in such large systems. Inertia, in this case, is predicted to keep a degree of human caused climate change in check, giving us more time to mitigate, respond, and adapt.

However, if human-caused temperature increase has resulted in an almost immediate response from the Arctic sea ice, then what does that mean for the land-based glaciers and floating ice shelves in Greenland and West Antarctica? Will the ongoing ocean/atmosphere temperature increase that appears to have driven such rapid change in the Arctic also result in rapid change there?

Given the extraordinary and ongoing loss of sea ice in the Arctic, it would seem that providing answers to these questions begs a degree of urgency. A collapse in Greenland and/or West Antarctica of any rough corollary to the nonlinear melt of Arctic sea ice could be a disaster without parallel in human history. And the sensitivity of Arctic sea ice to temperature change, at least, hints at much greater climate sensitivity in the world climate as a whole.

It may be that the Arctic sea ice is very sensitive for specific, identifiable reasons that do not make it a good model for overall climate change. But, if the opposite is true, we should at least be aware so that we can provide appropriate mitigation and adaptation policies. One would think, in such cases, that more resources would be provided to clarify and, as necessary, respond to these risks.

The graph below, produced by Climate Progress and based on a new study published in Science, shows how temperature is as warm now as it was 3,000 years ago. It also shows how the pace of increase is without corollary for any time during the last 11,300 years — the space in which human civilization developed.

Carbon-Final

Links:

http://www.skepticalscience.com/record-arctic-sea-ice-melt-to-levels-unseen-in-millennia.html

https://robertscribbler.wordpress.com/2012/08/30/arctic-sea-ice-melt-worst-seen-in-3000-years-summer-arctic-ocean-may-be-essentially-ice-free-within-5-20-years/

http://classic.wunderground.com/blog/JeffMasters/comment.html?entrynum=605&tstamp=&page=4

http://thinkprogress.org/climate/2013/03/08/1691411/bombshell-recent-warming-is-amazing-and-atypical-and-poised-to-destroy-stable-climate-that-made-civilization-possible/

National Center for Atmospheric Research Uncovers Growing Risk of a Fire Age: Doubling CO2 Equals More Than 7 Degrees of Warming

A study released last week from the National Center for Atmospheric Research (NCAR) showed that for each doubling of atmospheric CO2 content, the Earth’s climate warms by about 7-8 degrees Fahrenheit or around 4.5 degrees Celsius. The authors, John Fasullo and Kevin Trenberth found that the models predicting the greatest degree of warming were the most accurate. These models took into account the complex interplay of cloud formation and increasing levels of atmospheric water vapor due to heating.

This study’s findings more closely parallel indications seen in the geological record where CO2 doublings pushed temperature warming in the range of 5-6 degrees Celsius or more. It is also another indicator that persistent CO2 at current levels of near 400 ppm are enough to push global warming above the, very dangerous, 2 degree threshold. In fact, geological evidence has pointed to recent periods in Earth’s past when 400 ppm CO2 resulted in temperatures 3-4 degrees Celsius hotter than they are now.

The study’s findings are important due to the fact that scientists believe very damaging climate impacts begin to occur at 2 degrees Celsius above the 20th century average. However, massive Arctic sea ice melt, expanding desertification, extreme fire seasons, extreme heat waves, and increasingly intense storms show that very damaging effects are beginning now, at just less than a 1 degree Celsius global temperature increase.

Fast forward to the end of the 21rst century and we, under business as usual fossil fuel emissions, find ourselves at 1,400 ppm CO2 or more. The NCAR study would indicate that average world temperatures under such a situation will increase by 12-15 degrees Celsius. This massive temperature increase would be three times that of the difference between the current age and an ice age — but on the side of hot. An extreme fire age, if you will. This potential is also three times the current maximum temperature increase predicted in the most recent IPCC model scenarios.

Given this prospect and the growing clarity coming from climate model analysis, it is becoming ever more obvious that our fossil fuel consumption has already burned us out of the safe zone and is increasingly pushing us into a dangerous era of devastating climate impacts. A recent Discovery Magazine article analyzing the NCAR report somewhat joking called for climate change alarmism in an article entitled: Wanted: Global Warming Alarmists.

And it is true that global warming alarmism is indeed called for because, well, the world need a proper warning for what’s in store. Especially if we continue to subsidize fossil fuel production to the tune of half a trillion dollars each year and growing.

Links:

https://www2.ucar.edu/atmosnews/news/8264/future-warming-likely-be-high-side-climate-projections-analysis-finds

http://news.discovery.com/earth/wanted-global-warming-alarmists-121113.html

https://robertscribbler.wordpress.com/2012/08/29/moving-toward-a-fire-age-significant-global-temperature-impacts-and-predictions-for-21rst-century/

What Does a World at 400 Parts Per Million CO2 Look Like Long-Term?

In the give and take of the current global warming debate, it’s easy to lose track of context. Thankfully, we have a geological history to use as a window to our past. And by using that window we can see what the world will look like if CO2 levels stay where they are for long periods of time. In this first exploration, we’ll look at current CO2 levels — around 400 parts per million to give a decent idea of how the world will change if we don’t undertake the challenge of reducing these high levels of greenhouse gasses.

When Was the Last Time CO2 Levels Were This High?

It is important to note that relatively small changes in CO2 can lead to ample warming. During the last ice age, more than 10,000 years ago, CO2 levels were stable in a range between 180 and 210 parts per million. At the ice age’s cessation, CO2 levels rose to 280 parts per million. This relatively small rise of about 70 parts per million had dramatic consequences. Temperatures rose by about 5.5 degrees Celcius (10 degrees Fahrenheit).

Today, industrial activity and fossil fuel consumption has resulted in nearly 120 parts per million of additional CO2 added to the atmosphere. This addition has occurred over a very short time-scale when compared to past changes in CO2 levels and additions of 2-3 parts per million continue each year.

However, assuming CO2 were to stabilize. Assuming that, somehow, the world is able to reign in emissions enough to keep CO2 levels steady at 400 parts per million, what would happen?

As mentioned above, geological history gives us a basic notion. Long ago, about 3 million years ago, CO2 levels were steady in a range of 365-410 parts per million. This geological era was called the Pliocene.

What Did the Pliocene Look Like?

What would seem like a rather small difference in CO2 levels had dramatic effects. The first was that sea levels were 75 feet higher than they are currently today. The second was that average temperatures around the world were 3-4 degrees Celsius warmer (5.4-7.2 degrees Fahrenheit). Greenland and the West Antarctic Ice Sheet were ice free at CO2 levels of 400 parts per million and temperatures 3 degrees Celsius warmer than today. Arctic temperatures were much warmer — 8-16 degrees Celsius warmer than today.

This is the kind of world we can expect if CO2 levels are sustained at 400 parts per million.

Why Do Climate Models Under-predict Sea Level and Temperature Rise?

These historic temperature increases are much greater than those predicted by current climate models. The reason is that these models have not been able to take into account all the feedbacks to CO2 forcing that are intrinsic to the climate system. Models, by their nature, are simplifications and are only as good as the data that goes into them. But looking at geological history, it is quite clear that current climate models underestimate temperature and sea level rise given current levels of CO2.

How Fast Will Climate Change at a Constant 400 Parts Per Million CO2?

If, somehow, the world were able to stabilize CO2 at 400 parts per million, how fast would the world see 75 foot sea levels and 3-4 degree Celsius temperature increases? In short, this is the one million dollar question. Fossil fuel special interests would like us to believe that these changes would be gradual and slow to happen. In fact, many fossil fuel interests would have us believe that climate change isn’t happening at all, or, if it is, that its impacts will be far milder than the geological record would indicate. Sadly, the fossil fuel companies are misguiding themselves and the rest of us for their own short-term economic gain.

Paleoclimate data points to rapid, non-linear, responses to increases in CO2 levels. In some cases, temperatures have rebalanced over the course of decades and normally during periods of centuries or less. In some of the most radical cases, the changes have occurred on time scales measuring as few as ten years. Given the rapid rise of CO2 to its current state and likely feedbacks to result, we could expect to see a majority of that 75 feet in 300-600 years. That means severe consequences could ramp up before the end of this century pushing sea levels by ten to fifteen feet or more. You won’t see the IPCC posting a report that makes this kind of a statement, but it certainly is a potential, even if CO2 levels stabilize at ‘only’ 400 parts per million.

Most likely, current predictions of 1-2 meters of sea level rise by the end of this century is still a conservative forecast even for what would happen in a world where CO2 levels remain stable at 400 ppm. Even at constant CO2 levels of 400 ppm, we are looking at sea level rises in the range of 1.5-4.6 meters per century or more.

Business As Usual Estimates Place CO2 at Around 1000 Parts Per Million By the End of This Century; What Would That World Look Like?

Unfortunately, the world has yet to adopt serious policies that curtail greenhouse gas emission or reduce the level of CO2 in the atmosphere. And, even more concerning, world carbon sinks are beginning to contribute their own greenhouse gasses to the world climate system. Unless very rapid emissions reduction regimes are put into place, the world of the Pliocene, as strange and radically different as it may seem, will look like paradise compared to a world that reaches 600, 800, 0r 1000 parts per million CO2. And it is this increasing likelihood that we will explore in another blog.

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Links:

http://www.nasa.gov/topics/earth/features/rapid-change-feature.html

http://www.skepticalscience.com/what-was-it-like-the-last-time-co2-levels-were-this-high.html

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