Weather Extremes Provoked By Trapping Of Giant Waves In The Atmosphere, Likely Boosted By Global Warming

In October, a NOAA-led study found that “Warming-Driven Arctic Ice Loss Is Boosting Chance of Extreme U.S. Weather.” A new study offers another mechanism for warming to drive extreme weather — JR

Potsdam Institute for Climate Impact Research news release

The world has suffered from severe regional weather extremes in recent years, such as the heat wave in the United States in 2011 or the one in Russia 2010 coinciding with the unprecedented Pakistan flood. Behind these devastating individual events there is a common physical cause, propose scientists of the Potsdam Institute for Climate Impact Research (PIK). The study will be published this week in the US Proceedings of the National Academy of Sciences and suggests that man-made climate change repeatedly disturbs the patterns of atmospheric flow around the globe’s Northern hemisphere through a subtle resonance mechanism.

“An important part of the global air motion in the mid-latitudes of the Earth normally takes the form of waves wandering around the planet, oscillating between the tropical and the Arctic regions. So when they swing up, these waves suck warm air from the tropics to Europe, Russia, or the US, and when they swing down, they do the same thing with cold air from the Arctic,” explains lead author Vladimir Petoukhov.

“What we found is that during several recent extreme weather events these planetary waves almost freeze in their tracks for weeks. So instead of bringing in cool air after having brought warm air in before, the heat just stays. In fact, we observe a strong amplification of the usually weak, slowly moving component of these waves,” says Petoukhov. Time is critical here: two or three days of 30 degrees Celsius are no problem, but twenty or more days lead to extreme heat stress. Since many ecosystems and cities are not adapted to this, prolonged hot periods can result in a high death toll, forest fires, and dramatic harvest losses.

Anomalous surface temperatures are disturbing the air flows

Climate change caused by greenhouse-gas emissions from fossil-fuel burning does not mean uniform global warming – in the Arctic, the relative increase of temperatures, amplified by the loss of snow and ice, is higher than on average. This in turn reduces the temperature difference between the Arctic and, for example, Europe, yet temperature differences are a main driver of air flow. Additionally, continents generally warm and cool more readily than the oceans. “These two factors are crucial for the mechanism we detected,” says Petoukhov. “They result in an unnatural pattern of the mid-latitude air flow, so that for extended periods the slow synoptic waves get trapped.”

The authors of the study developed equations that describe the wave motions in the extra-tropical atmosphere and show under what conditions those waves can grind to a halt and get amplified. They tested their assumptions using standard daily weather data from the US National Centers for Environmental Prediction (NCEP). During recent periods in which several major weather extremes occurred, the trapping and strong amplification of particular waves – like “wave seven” (which has seven troughs and crests spanning the globe) – was indeed observed. The data show an increase in the occurrence of these specific atmospheric patterns, which is statistically significant at the 90 percent confidence level.

The probability of extremes increases – but other factors come in as well

“Our dynamical analysis helps to explain the increasing number of novel weather extremes. It complements previous research that already linked such phenomena to climate change, but did not yet identify a mechanism behind it,” says Hans Joachim Schellnhuber, director of PIK and co-author of the study. “This is quite a breakthrough, even though things are not at all simple – the suggested physical process increases the probability of weather extremes, but additional factors certainly play a role as well, including natural variability.” Also, the 32-year period studied in the project provides a good indication of the mechanism involved, yet is too short for definite conclusions.

Nevertheless, the study significantly advances the understanding of the relation between weather extremes and man-made climate change. Scientists were surprised by how far outside past experience some of the recent extremes have been. The new data show that the emergence of extraordinary weather is not just a linear response to the mean warming trend, and the proposed mechanism could explain that.

– Potsdam Institute for Climate Impact Research news release

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50 Years Ago Today, JFK Called For Closing A Giant Tax Loophole…But It Still Exists

Our guest blogger is Seth Hanlon, Director of Fiscal Reform at the Center for American Progress Action Fund.

On January 24, 1963, exactly half a century ago, President John F. Kennedy called on Congress to enact a broad overhaul of the tax code. One of JFK’s boldest proposals was to close a giant tax loophole that allows wealthy people to escape taxes on capital gains — the appreciation in value of stocks, businesses, or other investments — by holding onto assets until death and passing them onto heirs.

Though JFK’s successor, Lyndon Johnson, pushed through much of the Kennedy tax program in 1964, the tax break on inherited capital gains survived. It exists to this day as one of the largest loopholes in the tax code.

The provision is sometimes called the “angel of death loophole” or, in tax-speak, the “stepup in basis at death.” Here is how it works: Let’s say an investor buys stock for $1,000 and over time it shoots up in value to $100,000. If the investor sells that stock, he’ll owe capital gains taxes on the amount it has gone up.

But if the investor holds onto the stock his whole life and bequeaths it to his heirs, the $99,000 of gain is never subject to capital gains tax. The heirs inherit the stock with what’s called a “stepped-up basis,” which means that if they sell the stock at some point, they’ll only owe capital gains tax on any gain above $100,000.

The inherited capital gains loophole has major effects on the budget, on the economy, and on tax fairness. It results in about half of all capital gains going permanently untaxed. It costs the U.S. Treasury an estimated $50 billion per year (perhaps more). It encourages people to hold onto assets even when they would otherwise want to sell them. And since capital gains are highly concentrated at the top end of the income scale, it undermines progressivity.

One of the arguments for maintaining the inherited capital gains tax break is that the estate tax provides a backstop, ensuring that large inheritances are taxed. But that argument holds less water now that the estate tax has been largely eviscerated.

In submitting his tax reform proposal to Congress, Kennedy emphasized that eliminating “the ability to avoid all capital gains taxed on assets held until death” would mean that more investors would choose “the most desirable investment[s],” not the most tax-favored ones. JFK’s proposal included a number of exceptions to address practical issues, including exempting the vast majority of people with only modest amounts of capital gains. Unfortunately, however, Congress left the loophole untouched, and subsequent efforts to address it have also come up short.

Fifty years later, Congress is again discussing tax reform, and though the inherited capital gains loophole is one of the largest tax breaks, it is rarely debated. But if Congress is committed to a balanced approach to our fiscal challenges, and serious about “base broadening” tax reform, it should revisit a half-century-old proposal that is more relevant than ever.

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