A new report from the World Meteorological Organization confirms that the first decade of the 21st century was the warmest since meteorological records began around 1850; nine of the years between 2001 and 2010 were among the ten warmest ever recorded. And the increase from 1991-2000 to 2001-2010 was the largest decade-on-decade increase yet seen.
All of this is despite the prevalence of naturally cooling conditions such as La Niña for much of the decade. It has been, as the title of the WMO report notes, a decade of climate extremes; and with atmospheric greenhouse gas concentrations continuing to rise, there is no reason to believe that those extremes are going to diminish anytime soon.
But what, in practical terms, will that mean for most of us? Will the world feel much different for any of us? What are some of the things we'll have to deal with and endure as a result of a changing climate?
Eyewall of Hurricane Katrina, south of Louisiana landfall.
No surprise severe storms are first on the list. It's one of the topics that is most frequently raised in connection with climate change, and all the more so in the wake of last year’s Superstorm Sandy and this year’s deadly Oklahoma tornadoes.
Just how much will climate change play a role in putting people at risk from larger and more frequent storms? Some of the specific links are hard to make: weather is weather, and deadly storms have always happened. The link between climate change and tornadoes is uncertain and a little contradictory, as global warming appears to be affecting the two main drivers of tornadoes in opposite ways.
Meanwhile, the WMO report notes that 2001-10 was the most active decade since 1855 for tropical cyclones in the North Atlantic basin, with the most active year being 2005, with 27 named storms, of which the most powerful and devastating was of course Katrina. Most experts suspect that the quantity of tropical cyclones in the Atlantic may decrease, but that the severity of those that do form will increase. Only six years have seen the formation of more than one Category 5 hurricane, and two of those years were in the last decade - 2005 and 2007.
Weather is weather and climate is climate: extreme weather events - droughts, wildfires, blizzards, floods - have always happened and always will. Over the short term, natural variability will always remain the most significant driver of weather events. But if it is difficult and risky to ascribe particular weather events to climate change, weather is the most obvious manifestation of climate - or, as one researcher puts it, "climate trains the boxer, and weather throws the punches."
The rise in global temperatures doesn't mean that everywhere is simply going to get warmer; in many cases the prevalent weather conditions are going to become more extreme. In desert areas such as the southwest, that means more droughts and the risk of more frequent, more severe wildfires. In less arid areas such as the eastern seaboards or southern California, increased temperatures will allow the atmosphere to hold greater amounts of water vapor, leading to longer periods of greater rainfall - with a concomitant increased risk of flooding and landslides. Increased warming in the Arctic is causing heat to rise and disrupt the wind patterns that encircle the Arctic regions, causing cold polar conditions to crash into northern and midwestern states and create more frigid winters.
Another consequence of that Arctic warming? Altering the course of the jet stream, which transports weather systems around the globe from west to east. As a result, those weather systems are progressing less slowly, causing extreme conditions to be more persistent. In March 2012, for example, a massive dome of high pressure parked across the US east coast for more than a week, leading to an unseasonal heat wave.
Few industries are more dependent on ideal climatic conditions than agriculture - and few if any are as central to the underpinnings of civilization. In general terms, it is difficult to provide a blanket prediction of the impacts of climate change on agriculture: after all, increased temperatures and CO2 may prompt growth of some plant species, but in doing so may negatively impact their yields, by reducing the amount of time that seeds have to grow and mature.
And those temperature and CO2 increases may benefit weeds more than grains such as wheat or rice. In general, though, increasing temperatures and extreme weather events are likely to affect the range and viability of much agriculture.
Three grains - wheat, corn, and rice - support the bulk of the world's food intake, and the United States provides 30 percent of the global supply, so what happens here matters a great deal. According to a recent US government report, in the short term the industry is expected to prove quite resilient, but by the middle of the century, "the rising incidence of weather extremes will have increasingly negative impacts on crop and livestock productivity."
Some areas, such as California's central valley, will be especially hard hit, with not just wheat, corn and rice, but also sunflowers, tomato, and cotton expected to lose 10-30 percent of their yields.
Throughout the country, fruit and nut crops that depend on "winter chilling" days may have to relocate, as will crops that are already 'on the fringes,' such as maple. Animals exposed to many hot nights will become increasingly stressed. Many vegetable crops will be hit when temperatures rise only a few degrees above normal. With both crops and animals already stressed, the industry will be at yet greater vulnerability from extreme events such as drought, fires, and rainfall. Long story short: in the short term, don't expect too many disruptions, but expect increases in food prices, and periodic shortages of some crops, in the future.
Like to start your day with a cup or two of coffee? That may prove more difficult in future. The spread of a deadly coffee fungus has been linked to global warming; and last year, researchers with England's Royal Botanical Gardens suggested that rising temperatures could result in almost 100 percent of the places that grow the Arabica bean becoming unsuitable for the plant by 2080.
Feel like seeking solace from that kind of bad news by sneaking chunks of chocolate? Sorry, here's another downer: according to a 2011 report from the International Center from Tropical Agriculture, chocolate could, by mid-century, be a luxury item at best. The world's chocolate industry procures almost half its chocolate from cocoa farmers in the West African nations of Ghana and Cote d'Ivoire; but temperature increases could make the region too warm for the sensitive trees to grow.
It hasn't been a good few years for honey bees, particularly in Europe and the United States. Since 2006, Colony Collapse Disorder has caused the loss of about 10 million beehives; and while the cause of that appears to be a combination of a species of parasitic mite, several viruses, a bacterial disease and the use of insecticides, a honey bee population that is already struggling does not need the extra challenges posed by climate change.
Earlier springs may cause plants to bloom before bees can awaken from hibernation to pollinate them; conversely, warmer winters may keep them too active and cause them to starve. That isn't just bad news for lovers of honey, but for those who like just about anything that bees pollinate - such as, writes Bryan Walsh in Time Magazine, "cashews, beets, broccoli, cabbage, Brussels sprouts, chestnuts, watermelons, cucumber, fennel, strawberries, macadamia, mangoes, apricots, almonds or any of the other dozens of food crops pollinated by our hardworking, six-legged, unpaid farmworkers."
The Asian tiger mosquito (Aedes albopictus) is as bloodthirsty as it sounds.
Extreme conditions can have extreme health consequences, with those on the society's fringes - the poor, the very young, the elderly and the infirm - at special risk. They are the ones least likely to be able to flee from severe storms or flooding, and most likely to suffer during prolonged heat.
Hotter summers can make disease-carrying insects more active and for longer, potentially allowing the spread of illnesses like dengue fever and West Nile disease. Hotter days can also increase allergenic pollen and reduce air quality. Rainfall and flooding increase the danger of waterborne diseases and reduce the availability of potable water.
Although 80 percent of the population of the United States lives in urban regions, 95 percent of U.S. land area is classified as rural. And, as a U.S. government report notes, "Rural America’s importance to the country’s economic and social well-being is disproportionate to its population, since rural areas provide natural resources that much of the rest of the U.S. depends on for food, energy, water, forests, recreation, national character, and quality of life."
That same report points out that rural America has "already experienced some of the impacts of climate change related weather effects," including crop and livestock loss from severe drought and flooding, infrastructure damage to levees and roads from extreme storms, and large-scale losses from fires and other weather-related disasters. Because many rural communities are less economically diverse, and more natural resource-dependent, than their urban and suburban counterparts, they are likely to be disproportionately affected by climate changes and weather extremes.
Not all changes will be negative: whereas, for example, tourism to the Florida Everglades will diminish as sea level rises, tourism in coastal Maine may improve as temperatures increase.
One factor to watch out for: water. Extreme weather events like heat waves and rainfall are likely to increase soil erosion rates, increasing deposition of nitrogen and phosphorous into water bodies. In some regions, demands for water for irrigation, for example, will only increase, even as water availability diminishes.
Sunset over sea ice in the Beaufort Sea, off Oliktok point on Alaska's North Slope.
The disappearance of Arctic sea ice has in many ways become the iconic image of climate change - and whereas for most of us, it is an issue that does not feel directly relevant (unless we care deeply about polar bears or make the connection between declining sea ice and severe winter weather), for one segment of the population it's a very significant deal indeed.
For Inupiat and Yupik Eskimo communities in Alaska, thinning and retreating sea ice, along with earlier ice break-up in the spring and later formation in the fall, are already making vital subsistence hunting of seals, walruses and whales less certain and more dangerous. As sea ice retreats, it also leaves coastal settlements vulnerable to storm surges, which eat away at the land, placing those communities at risk, forcing their relocation and turning them into, in the words of Suzanne Goldenberg of The Guardian, "America's first climate refugees."
For many of us, climate change impacts are in the distance or, at best, around the corner. For some Americans, they are here right now.