Weather 2000 - FAQ Title Graphic

Q: We have seen a lot of hurricanes in recent years. Is the increase in tropical activity a result of global warming?
A: This is a very complex subject that is being debated in the scientific community. There is widespread agreement that the multidecadal fluctuations in the Atlantic Ocean (known as the AMO) directly contribute to the number of storms in the Tropical Atlantic since 1995. What is still very much up for debate is whether global warming has allowed storms to be more intense than they would have been otherwise. Certain studies indicate more intense storms are likely, while others indicate there will be fewer storms globally. This will continue to be diligently researched in the coming years.
Q: It doesn't seem like we experience those real brutal winters anymore. There has to be a warming trend, right?
A: Trends can be misleading. Examining 30, 40 or even 50 years worth of historical data might only encompass 10 - 20% of the full potential of climate variability. Since quality data only goes back 50 years at best, standard deviations and extreme records based on that data can be gross underestimations, and trends can overestimate the true climate state.

For example, there was a disproportionate number of El Niño events during the 1990's. In many areas in the Northeast and Mid-West this has led (along with other factors) to mild winters. This has caused the false assumption that these locations have permanent warming trends, perhaps also enhanced by the Urban Heat Island Effect, when in actuality it is often coincidental natural climate variability. More recently, the Winters of 2002-03 and 2003-04, show that long and harsh winters are still a very real threat.

Q: For locations which have been substantially warm during the past decade, is the possibility of opposite cold conditions eliminated?

Sacramento Warming Trend

It is very dangerous to draw conclusions based on the most recent 5 or 10 years worth of historical data. Although urbanization and micro-climate changes may cause a particular location to be somewhat milder in the decades to come on average, each upcoming year should be examined on a case by case basis. Dramatic season to season swings in temperature are quite possible despite recent "trends", and can be anticipated with Site-Specific Long Range Forecasting.
Q: What is the Urban Heat Island Effect?
A: smoky cityDue to population growth and urbanization, many metropolitan locations have become anomalously warm over the last 10 - 20 years. Because this is primarily a human-caused effect, it is classified as an anthropogenically-forced trend. A combination of deforestation, surface pollution, waste heat from electronics, and a buildup of concrete, asphalt and metal structures has created "bubbles" or "islands" of heat as observed by surface thermometers and as seen when viewed by Infrared satellite imagery: hence the name.
Q: Is this why some cities were so incredibly hot during recent summers?
A: It probably had a relatively small impact. The Urban Heat Island Effect is primarily a winter phenomenon, and has the most direct impact on inflating overnight minimum temperatures. To a lesser extent it affects maximum temperatures, storm dynamics and summer temperatures. Summer heat waves are caused by other atmospheric processes.
Q: Could the Urban Heat Island Effect be skewing observations regarding global warming?
A: Yes, but slightly. This is why a broad geographic sampling (both urban and rural) as well as mid-atmospheric temperature estimations are essential when analyzing the Global Warming question.
Q: So will all locations just get warmer and warmer as time goes on?
A: No. The media has over dramatized the consequences of Global Warming to the public. Images of steamy, tropical weather conditions covering the entire Earth in the next century support people's misconceptions. Although the Earth as a whole might warm, the warming is much more gradual than depicted. The Intergovernmental Panel on Climate Change (IPCC Third Assessment Report 2001) gives a range of expected warming between a 1.5 and 5.8 °C global temperature rise by the year 2100. Additionally, some locations of the Earth might actually cool by other complex ocean-atmosphere interactions. In the decades to come, larger temperature swings and variations, more extreme drought and flooding, increased coastline erosion, and more frequent and severe storms are possible.
Q: Speaking of cooling, will global warming cause us to plunge into an ice age virtually overnight?
A: While it is true that some scientists believe global warming may cause regional cooling, the media, along with Hollywood movies such as "The Day After Tomorrow", have over-dramatized this as well. Such a process would not happen over days and weeks as portrayed in the movies, but rather decades and centuries, or possibly not at all. Abrupt Climate Change, however, remains a concern, with a recent report by the National Acadamy of Sciences stating "available evidence suggests that abrupt climate changes are not only possible but likely in the future, potentially with large impacts on ecosystems and societies."