 40 years ago, in the United States, Kerry Manuel became a registered Republican. As an undergraduate at MIT in the 1970s, his classmates far left pro-communist views horrified him. Today, politically, not much has changed for him. He still thinks highly of conservative icons like Ronald Reagan. He still mostly votes Republican. But Dr. Manuel also happens to be the Cecil and Ida Green Professor of Atmospheric Science at MIT. He's a leading expert in the field of hurricane research. And now he gets email threats from other conservatives. Because Emmanuel doesn't just study hurricanes. He studies the ways in which human-caused global warming can make hurricanes more destructive in a warming world. How did a conservative undergraduate end up as the face of global warming's impact on hurricanes? By following the science. The science of hurricanes tells us rising sea levels, heavier rains, stronger winds, and warmer ocean water will cause hurricanes to grow stronger as we warm the planet. One of the most damaging effects of hurricanes is their storm surge. Hurricanes' powerful winds pile up enormous volumes of water. The low pressure center of hurricanes allows ocean level to rise higher. Together, these create a towering supply of water, waves right on top of this surge. In a world without climate change, hurricanes still produce storm surges. But as we continue to heat up the planet, we cause sea levels to rise. This increase in the underlying sea level makes the storm surge from hurricanes even larger in a warming world. That means storm surges can do more damage over the same area and reach areas much further inland than before. A recent report by Lloyds of London, an insurance firm, looked at the effect of sea level rise in hurricane Sandy. They estimate that the relatively small amount of sea level rise we've already had increased hurricane Sandy's damages by 30%, or around 8 billion US dollars in New York alone. In addition to storm surge, hurricanes produce torrential rains. The warm, moist air they pull up from the ocean cools and condenses as it rises, causing massive rainfall. As we warm the planet, the heavy rains from hurricanes are expected to become even heavier. These range drenched coastal areas, which combines with the storm surge to cause massive flooding. Hurricanes are also destructive because of their fierce winds. As we continue to heat up the planet, the maximum wind speeds of hurricanes are expected to get even faster. Hurricanes form in the tropics for a reason. They depend on hot ocean temperatures relative to the coolness of the air above. As we warm the planet, this can provide more fuel for hurricanes, making them more powerful. Studies looking at this question using many different methods have begun to reach agreement. A warming world will have stronger storms. But not all of the changes to hurricanes in a warming world will make them worse. If ocean temperatures are hurricane fuel, wind shear is hurricane kryptonite. Wind shear is just the difference in wind speed at different heights in the atmosphere. When wind speed is pretty much the same down low as it is higher up, hurricanes can grow strong. When wind shear is high, that is when wind speeds are different at different levels of the atmosphere, hurricanes get ripped apart. As humans warm the planet, some places where hurricanes form may see an increase in wind shear. That means that for these areas, hurricanes may grow more intense but also break up more often as they try to form. So we may see somewhat fewer but more powerful storms overall. Hurricanes are also pushed around the ocean by prevailing winds. These steering winds might also change as we heat the planet. For some areas, that might mean more storms get pushed away from land. And for other areas, that might mean more storms make landfall. But this too remains an area of active research. But climate science denialists reject even the most solid links between climate change and hurricanes. They say that hurricanes have always happened. They point to devastating storms that occurred in the past when human influence on the climate was smaller than it is today. They point to short periods without a major hurricane as evidence that nothing is changing. They are sure there is no link between global warming and hurricanes. A closer look at these claims reveal that they don't actually challenge the scientific links between warming and hurricanes at all. Rather, these claims rely on a number of fallacies coming to science denial. One of the most pervasive is oversimplification. Of course, hurricanes, even terrifically powerful ones, have happened in the past. And sure, they've happened when greenhouse gas levels were much lower than they are today. But that's not the whole story. We know that hurricanes are affected by a number of environmental factors. One of the strongest is the hot ocean temperatures. Looking back over hundreds of years, we can see that hurricanes have gotten stronger in response to natural increases in ocean temperature. This strengthens our confidence that hurricanes will get stronger as humans warm the ocean relative to the atmosphere. Climate science denialists are also fond of pointing to periods with low hurricane activity to deny a link with global warming while ignoring the bigger picture. This is a common science denial tactic called cherry picking. They point out that in recent years, the North Atlantic has not had as many dramatic storms as the mid-2000s. However, the overall picture since we've had accurate observations points to an increase in hurricane activity and that this increase is strongly tied to warming ocean temperatures. And when we reconstruct storm activity over hundreds of years, we see a similarly close relationship. Based on flawed reasoning, climate science denialists jump to a faulty conclusion. They draw the wrong lessons from what observations and history tell us about hurricane behavior. During his research, Kerry-Manuel has flown into the eye of a real-world hurricane. And although his findings have put him in the middle of a political storm, the science doesn't care about politics. How hurricanes will change in a warming climate is an area of active research, but some links to warming have become clear. As humans warm the planet, rising sea level, heavier rains, stronger winds, and warmer ocean water will increase the destructive potential of these massive storms.