We are in a state of planetary emergency. The stability and resilience of our planet are in peril. International action — not just words — must reflect this. Timothy Lenton , Johan Rockström , et al,.
The climate is going to hell in a handbasket, and Donald Trump did his best to sabotage every single effort in the global fight against climate change. We all know the man is a traitor, seditionist, pedophile, sociopath, and some say those are his better qualities.
I go further in my estimation of him. He is a monster, the incubus, a man hell-bent on killing every single lifeform on earth if given his way. He and his henchmen had four years to destroy all that was good and he did not waste a minute of it.
But I could rage against him for hours but the climate doesn’t care. It’s physics, and it will do what it’s going to do to our detriment.
When Trump was installed by Putin, Comey, and social as well as traditional media cooing over him for the entire 2016 campaign, one of his first targets to destroy was the agencies tasked with saving the climate and the environment.
The primary target was the EPA, he had all references to the climate, environment, and social justice removed from government websites.
In May, the administration of Joe Biden and Kamala Harris reinstated and updated and restored the deleted pages.
In some ways, the big picture about climate change right now is obvious. Still, it’s a good idea to keep an eye on the data. Trump’s administration took down the EPA’s excellent Climate Change Indicator webpages, but under Biden’s leadership, they have been updated and restored for the public. Here is an informative version of this story (Dino Grandoni and Brady Dennis, Washington Post), and here (Mark Kaufman, Vox) is a good sample of the new graphics, presented with some appropriate modifiers: grim, stark, extreme, incessant, exceptional … For another vivid set of graphics based on NOAA data but with a Canadian perspective, see here (Barry Saxifrage, National Observer).
Such graphics generally show gradual increases in the relevant numbers. But it’s very likely that some changes to our planet will involve tipping points – small increments with disproportionately large effects, as, say, when just a fraction of a degree of warming transforms ice to water. Here (Alexandria Herr, Shannon Osaka, Maddie Stone, Grist) is a terrific look at some of the largest likely “Points of No Return” that may occur not too far in the future.
As usual, whether or when we reach these physical tipping points depends largely on what we humans do in coming years. For that topic, the idea of “social tipping points” is useful, if still underdeveloped. David Roberts (Vox) offers a typically clear explainer here, as does Marlow Hood (Phys.org) here. It’s worth the time to read both.
Key Points
Global atmospheric concentrations of carbon dioxide, methane, nitrous oxide, and certain manufactured greenhouse gases have all risen significantly over the last few hundred years (see Figures 1, 2, 3, and 4).
Historical measurements show that the current global atmospheric concentrations of carbon dioxide, methane, and nitrous oxide are unprecedented compared with the past 800,000 years (see Figures 1, 2, and 3).
Carbon dioxide concentrations have increased substantially since the beginning of the industrial era, rising from an annual average of 280 ppm in the late 1700s to 410 ppm in 2019 (average of five sites in Figure 1)—a 46 percent increase. Almost all of this increase is due to human activities.1
The concentration of methane in the atmosphere has more than doubled since preindustrial times, reaching over 1,800 ppb in recent years (see the range of measurements for 2019 in Figure 2). This increase is predominantly due to agriculture and fossil fuel use.2
Over the past 800,000 years, concentrations of nitrous oxide in the atmosphere rarely exceeded 280 ppb. Levels have risen since the 1920s, however, reaching a new high of 331 ppb in 2019 (average of three sites in Figure 3). This increase is primarily due to agriculture.3
Concentrations of many of the halogenated gases shown in Figure 4 were essentially zero a few decades ago but have increased rapidly as they have been incorporated into industrial products and processes. Some of these chemicals have been or are currently being phased out of use because they are ozone-depleting substances, meaning they also cause harm to the Earth’s protective ozone layer. As a result, concentrations of many major ozone-depleting gases have begun to stabilize or decline (see Figure 4, left panel). Concentrations of other halogenated gases have continued to rise, however, especially where the gases have emerged as substitutes for ozone-depleting chemicals (see Figure 4, right panel).
Overall, the total amount of ozone in the atmosphere decreased by about 3 percent between 1979 and 2018 (see Figure 5). All of the decreases happened in the stratosphere, with most of the decrease occurring between 1979 and 1994. Changes in stratospheric ozone reflect the effect of ozone-depleting substances. These chemicals have been released into the air for many years, but recently, international efforts have reduced emissions and phased out their use.
Globally, the amount of ozone in the troposphere increased by about 13 percent between 1979 and 2018 (see Figure 5).
Ocean heat content
Key Points
In four different data analyses, the long-term trend shows that the top 700 meters of the oceans have become warmer since 1955 (see Figure 1). All three analyses in Figure 2 show additional warming when the top 2,000 meters of the oceans are included. These results indicate that the heat absorbed by surface waters extends to much lower depths over time.
Although concentrations of greenhouse gases have risen at a relatively steady rate over the past few decades (see the Atmospheric Concentrations of Greenhouse Gases indicator), the rate of change in ocean heat content can vary from year to year (see Figures 1 and 2). Year-to-year changes are influenced by events such as volcanic eruptions and recurring ocean-atmosphere patterns such as El Niño.
Ocean Acidity
Key Points
Measurements made over the last few decades have demonstrated that ocean carbon dioxide levels have risen in response to increased carbon dioxide in the atmosphere, leading to an increase in acidity (that is, a decrease in pH) (see Figure 1).
Historical modeling suggests that since the 1880s, increased carbon dioxide has led to lower aragonite saturation levels in the oceans around the world, which makes it more difficult for certain organisms to build and maintain their skeletons and shells (see Figure 2).
The largest decreases in aragonite saturation have occurred in tropical waters (see Figure 2); however, decreases in cold areas may be of greater concern because colder waters typically have lower aragonite saturation levels to begin with.4
U.S. and Global Temperature
Key Points
Since 1901, the average surface temperature across the contiguous 48 states has risen at an average rate of 0.16°F per decade (see Figure 1). Average temperatures have risen more quickly since the late 1970s (0.31 to 0.54°F per decade since 1979). Eight of the top 10 warmest years on record for the contiguous 48 states have occurred since 1998, and 2012 and 2016 were the two warmest years on record.
Worldwide, 2016 was the warmest year on record, 2020 was the second-warmest, and 2011–2020 was the warmest decade on record since thermometer-based observations began. Global average surface temperature has risen at an average rate of 0.17°F per decade since 1901 (see Figure 2), similar to the rate of warming within the contiguous 48 states. Since the late 1970s, however, the United States has warmed faster than the global rate.
Some parts of the United States have experienced more warming than others (see Figure 3). The North, the West, and Alaska have seen temperatures increase the most, while some parts of the Southeast have experienced little change. Not all of these regional trends are statistically significant, however.
Heavy Precipitation
Key Points
In recent years, a larger percentage of precipitation has come in the form of intense single-day events. Nine of the top 10 years for extreme one-day precipitation events have occurred since 1996 (see Figure 1).
The prevalence of extreme single-day precipitation events remained fairly steady between 1910 and the 1980s, but has risen substantially since then. Over the entire period from 1910 to 2020, the portion of the country experiencing extreme single-day precipitation events increased at a rate of about half a percentage point per decade (see Figure 1).
The percentage of land area experiencing much greater than normal yearly precipitation totals increased between 1895 and 2020. There has been much year-to-year variability, however. In some years there were no abnormally wet areas, while a few others had abnormally high precipitation totals over 10 percent or more of the contiguous 48 states’ land area (see Figure 2). For example, 1941 was extremely wet in the West, while 1982 was very wet nationwide.3
Figures 1 and 2 are both consistent with other studies that have found an increase in heavy precipitation over timeframes ranging from single days to seasons to years.4 For more information on trends in overall precipitation levels, see the U.S. and Global Precipitation indicator.
Temperature and Drought in the Southwest
Key Points
Every part of the Southwest experienced higher average temperatures between 2000 and 2020 than the long-term average (1895–2020). Some areas were more than 2°F warmer than average (see Figure 1).
Large portions of the Southwest have experienced drought conditions since weekly Drought Monitor records began in 2000. For extended periods from 2002 to 2005 and from 2012 to 2020, nearly the entire region was abnormally dry or even drier (see Figure 2).
Based on the long-term Palmer Index, drought conditions in the Southwest have varied since 1895. Since the early 1900s, the Southwest has experienced wetter conditions during three main periods: the 1900s, 1940s, and 1980s. Drier conditions occurred through the 1920s/1930s, again in the 1950s, and since 1990, when the Southwest has seen some of the most persistent droughts on record (see Figure 3).
Climate Forcing
Key Points
In 2019, the Annual Greenhouse Gas Index was 1.45, which represents a 45-percent increase in radiative forcing (a net warming influence) since 1990 (see Figure 1).
Of the greenhouse gases shown in Figure 1, carbon dioxide accounts for by far the largest share of radiative forcing since 1990, and its contribution continues to grow at a steady rate. Carbon dioxide alone would account for a 36-percent increase in radiative forcing since 1990.
Although the overall Annual Greenhouse Gas Index continues to rise, the rate of increase has slowed somewhat since the baseline year 1990. This change has occurred in large part because methane concentrations have increased at a slower rate in recent years and because chlorofluorocarbon (CFC) concentrations have been declining, as production of CFCs has been phased out globally due to the harm they cause to the ozone layer (see Figure 1).
Greenhouse gases produced by human activities have caused an overall warming influence on the Earth’s climate since 1750. The largest contributor to warming has been carbon dioxide, followed by methane and black carbon. Although aerosol pollution and certain other activities have caused cooling, the net result is that human activities on the whole have warmed the Earth (see Figure 2).
