Now that we have shown that the CO2 hypothesis has no merit whatsoever at the present level of human CO2 output, we have a problem. Why did the northern Hemisphere actually warm up so nicely? It is very much as if a switch got turned on somewhere and the result was the nice delivery ever year of an additional trainload of heat
This is a pretty serious problem. The scope of this heat switch is sufficient to eliminate the Arctic sea ice inside of about fifty years. It had been hard at work for at least thirty years before anyone clued in that it was even happening.
The good news is that it is presently warming us up. The bad news is that if it had switched the same amount of heat into the Southern Hemisphere it would readily produce a little ice age for the Northern Hemisphere. My point is that now that we have ruled out the CO2 proposition as unsupportable, we still have to locate the physical switch.
I also think that we can rule out the sun itself. It is an important factor that definitely produces climatic variation, but within a fairly narrow channel that is readily buffered by the atmosphere. Yet the pace of variation does not match the long cycle that we are now seeing and this makes it rather unlikely. So we cannot look to the sun for our decadal switching mechanism.
What we are really seeing is a decadal balancing of energy between the northern and southern hemispheres that allows the global heat budget to be properly restored and balanced. The system needs to exist and it needs to work.
That basically leaves us with one viable option that is able to actually do the job. I suggest that the flow rate of the deep counter current is varied. We already have a clue from our knowledge that the volume of the Gulf Stream has also slowed. This implies a longer dwell time for heat moved up on that conveyor belt. It also implies a lower throughput on the counter current. The effect would be to warm up the Arctic and the Northern Hemisphere. A southern counter to that would shove heat toward the Antarctic Peninsula conforming nicely to observation.
A modification in heat delivery out of the Atlantic would have the observed impact over the past decades. It would also cause the little ice age. In fact, we need look no further for an agent of temperature change. We simply do not know the details. We have a powerful mechanism that appears to behave decadally and is also linked directly to the countercurrents in the Pacific. We know almost nothing about it. We only know that the glove fits and this is a proper research target.
Climatologists Baffled by Global Warming Time-Out
Global warming appears to have stalled. Climatologists are puzzled as to why average global temperatures have stopped rising over the last 10 years. Some attribute the trend to a lack of sunspots, while others explain it through ocean currents.
At least the weather in
Otherwise, however, not much is happening with global warming at the moment. The Earth's average temperatures have stopped climbing since the beginning of the millennium, and it even looks as though global warming could come to a standstill this year.
Ironically, climate change appears to have stalled in the run-up to the upcoming world summit in the Danish capital, where thousands of politicians, bureaucrats, scientists, business leaders and environmental activists plan to negotiate a reduction in greenhouse gas emissions. Billions of euros are at stake in the negotiations.
Reached a Plateau
The planet's temperature curve rose sharply for almost 30 years, as global temperatures increased by an average of 0.7 degrees Celsius (1.25 degrees Fahrenheit) from the 1970s to the late 1990s. "At present, however, the warming is taking a break," confirms meteorologist Mojib Latif of the Leibniz Institute of Marine Sciences in the northern German city of
Even though the temperature standstill probably has no effect on the long-term warming trend, it does raise doubts about the predictive value of climate models, and it is also a political issue. For months, climate change skeptics have been gloating over the findings on their Internet forums. This has prompted many a climatologist to treat the temperature data in public with a sense of shame, thereby damaging their own credibility.
"It cannot be denied that this is one of the hottest issues in the scientific community," says Jochem Marotzke, director of the Max Planck Institute for Meteorology in
Just a few weeks ago,
The differences among individual regions of the world are considerable. In the
Mixed Messages
But a few scientists simply refuse to believe the British calculations. "Warming has continued in the last few years," says Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research (PIK). However, Rahmstorf is more or less alone in his view. Hamburg Max Planck Institute scientist Jochem Marotzke, on the other hand, says: "I hardly know any colleagues who would deny that it hasn't gotten warmer in recent years."
The controversy sends confusing and mixed messages to the lay public. Why is there such a vigorous debate over climate change, even though it isn't getting warmer at the moment? And how can it be that scientists cannot even arrive at a consensus on changes in temperatures, even though temperatures are constantly being measured?
The global temperature-monitoring network consists of 517 weather stations. But each reading is only a tiny dot on the big world map, and it has to be extrapolated to the entire region with the help of supercomputers. Besides, there are still many blind spots, the largest being the
The scientists at the
Marotzke and Leibniz Institute meteorologist Mojib Latif are even convinced that the fuzzy computing done by Rahmstorf is counterproductive. "We have to explain to the public that greenhouse gases will not cause temperatures to keep rising from one record temperature to the next, but that they are still subject to natural fluctuations," says Latif. For this reason, he adds, it is dangerous to cite individual weather-related occurrences, such as a drought in
"Perhaps we suggested too strongly in the past that the development will continue going up along a simple, straight line. In reality, phases of stagnation or even cooling are completely normal," says Latif.
Part 2: The Difficulties of Predicting the Climate
Climatologists use their computer models to draw temperature curves that continue well into the future. They predict that the average global temperature will increase by about three degrees Celsius (5.4 degrees Fahrenheit) by the end of the century, unless humanity manages to drastically reduce greenhouse gas emissions. However, no one really knows what exactly the world climate will look like in the not-so-distant future, that is, in 2015, 2030 or 2050.
This is because it is not just human influence but natural factors that affect the Earth's climate. For instance, currents in the world's oceans are subject to certain cycles, as is solar activity. Major volcanic eruptions can also curb rising temperatures in the medium term. The eruption of
But the
Weaker Solar Activity
The fact is that the sun is weakening slightly. Its radiation activity is currently at a minimum, as evidenced by the small number of sunspots on its surface. According to calculations performed by a group of NASA scientists led by David Rind, which were recently published in the journal Geophysical Research Letters, this reduced solar activity is the most important cause of stagnating global warming.
Latif, on the other hand, attributes the stagnation to so-called Pacific decadal oscillation (PDO). This phenomenon in the
With his team at the Leibniz Institute of Marine Sciences, Latif has been one of the first to develop a model to create medium-term prognoses for the next five to 10 years. "We are slowly starting to attempt (such models)," says Marotzke, who is also launching a major project in this area, funded by the Federal Ministry for Research and Technology.
Despite their current findings, scientists agree that temperatures will continue to rise in the long term. The big question is: When will it start getting warmer again?
If the deep waters of the Pacific are, in fact, the most important factor holding up global warming, climate change will remain at a standstill until the middle of the next decade, says Latif. But if the cooling trend is the result of reduced solar activity, things could start getting warmer again much sooner. Based on past experience, solar activity will likely increase again in the next few years.
Betting on Warmer Temperatures
The
While climatologists at conferences engage in passionate debates over when temperatures will start rising again, global warming's next steps have also become the subject of betting activity.
Climatologist Stefan Rahmstorf is so convinced that his predictions will be correct in the end that he is willing to back up his conviction with a €2,500 ($3,700) bet. "I will win," says Rahmstorf.
His adversary Latif turned down the bet, saying that the matter was too serious for gambling. "We are scientists, not poker players."
Translated from the German by Christopher Sultan
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