Climate NewsNOAA: Climate.gov
Natl. Center for Atmospheric Research
NASA Earth Observatory
National Sea Ice Data Center
Tropical & Hurricane Weather
Grist.org: Answers to Climate Skeptics
350.org: Global Warming Math
National Geographic: Global Warming
The Best Brief Climate ExplainerClimate Change in Pictures and Data: Just the Facts
Current ConditionsGlobal Sea Surface Temperature
US Pacific Sea Surface Temperature
Atmospheric CO2 at Mauna Loa Observatory.
The black line is CO2 concentration, showing seasonal variation on top of the upward trent. The red line represents 57% of cumulative industrial emissions from fossil fuels that are estimated to remain airborne, showing the close link between the two. (Click image for larger version or more info here.)
Dissipation of multi-year Arctic sea ice, 1987-Present
"When you have the largest Atlantic storm in recorded history that is being fed by unusually warm ocean waters (+5°F) and is being steered in a very unusual direction by a “3-sigma” blocking high over Greenland after the largest Arctic sea ice melt in human history, you might want to consider the “steroid” hypothesis a bit more." -- Dan Miller, on Hybrid Storm Sandy
Climate Change & the Ocean: A Journey Through the ScienceFeaturing Climate Change: Lines of Evidence, video series by the National Academy of Sciences.
For students: There are 6 sections of reading, videos, web links and images. Each section has a set of questions at the end to complete as a class assignment.
Part 2 of the series describes the types of evidence we have that the planet is warming.WATCH: Climate Change, Lines of Evidence: Is Earth Warming?
Climate data is collected and analyzed by many independent groups of scientists, and there is virtually unanimous consent that A) the planet is warming, and B) human use of fossil fuel is the cause. A few non-climate scientists who were skeptical of the methods used to calculate global temperature recently did an exhaustive reanalysis of 250 years of data. Their results, published this year (at left) affirmed the interpretation was correct, and was only consistent with fossil fuel usage. (The down-blips are when there were volcanos. Click on image for more info.)
In 2009, the American Association for the Advancement of Science led 18 scientific societies in a letter to the U.S. Senate affirming consensus on the scientific basis of global warming. (See the letter here.) To see a list of scientific societies from around the world who have also endorsed this consensus, scroll down the page here: Is there a scientific consensus on global warming?
These two datasets of atmospheric CO2 were shown in the video:
What are all the bumps and zigzags?
The top image is called the Keeling Curve, after the Scripps scientist who started the observations. The "zig-zags" in the data show the seasonal variation in CO2. During winter, CO2 levels go up slightly because of plants dying back and decaying. During summer, CO2 levels go down because of renewed plant growth that consumes it.
The bottom image is the longest record of atmospheric CO2 to date. The humps in the data represent much longer time periods: glacial and interglacial periods (glacial periods = "ice ages"). During warm interglacial periods, CO2 is higher, and during cold glacial periods it is lower.
The seasonal and glacial cycles are the primary types of natural variability in the CO2 record.
...Click on the bottom image for more information on the source...
So you can see, a few hundred parts per million can make a big difference in transmission of radiation. (And actually in the demo, we were only looking at 28 and 56 ppm, because the ink was already diluted to 1/10th of its original strength.)
Sources and sinks. When asking the question, "Does the rise in CO2 come from fossil fuel usage," it's important to consider what the other options are. If it is not coming from fossil fuels, there would have to be 1) a mysterious, unknown source, and 2) it would have to explain the data better than fossil fuel usage. What we know about the volume of industrial sources indicates that what we measure in the air is in fact only part of total global emissions. About 40% has been absorbed by the ocean. If the CO2 in the air comes from somewhere else, there would also have to be a very large unknown sink that is absorbing the fossil fuel emissions. So the options are: fossil fuel emissions, which agree with the CO2 record in both timing and quantity, or Mysterious Sources and Sinks. Science points toward known facts. (See how the Keeling Curve matches fossil fuel emissions.)
Carbon gives itself away. There are in fact even more lines of evidence pointing toward fossil fuels, such as the "forensic evidence" mentioned in the video. Carbon is made up of several different isotopes -- varieties of the atom that have different numbers of neutrons. These isotopes are incorporated into biomass in different ways because of their different weights. The excess CO2 in the atmosphere has the isotopic signature of carbon that comes from biological material, as opposed to something like volcanic or geologic activity. RealClimate.org has a nice explainer of how the isotopic forensics works.
The next part of the video details some of the changes that are happening on earth because of the excess CO2 in the atmosphere.WATCH: Climate Change, Lines of Evidence: How much warming?
This summer (2012) arctic ice melted back further than any year on record, and well past the last record set in 2007. In light of this acceleration, scientists now think the Arctic may be ice-free in the summer within 5-10 years. The image at the right shows the difference in multi-year summer ice cover between 1980 and 2012. (Multi-year ice is thicker and more resilient than single-season ice, because it has accumulated for several years or more.) By the end of summer, Arctic ice cover in 2012 was 18% less than the previous record set in 2007. The new animation at the top of this site shows the progression of this multi-year ice melt over the last 25 years, from 1987-2012. In it you can see the dissipation as well as the movement of thick multi-year ice. The image at the left shows where the ice cover is today, and you can see how much more melted this year than in the record warm year of 2007.
The following presentation, "Ocean Acidification: Starting with the Science" shows the wide-ranging impact of the oceans absorbing large amounts of CO2.Ocean Acidification: Starting with the Science
Many of the effects on the ocean and coasts are discussed in the report Global Climate Change Impacts in the U.S., as well as in these articles (and many others):An Illustrated Guide to the Science of Global Warming Impacts
Caribbean Coral Reefs Mostly Dead
Record loss of Arctic ice may trigger extreme weather
Expedition to study changes in ocean salinity
Sea Level Rise Projections and Impacts
Sea Level Rise Accelerating on U.S. Atlantic Coast
Where are we headed? The current level of total global CO2 emissions is shown below, by the black line. The colored lines represent hypothetical emissions rates for different global warming scenarios, from best case (B2) to worst (A1F1). The dip in actual emissions in 2008-2009 was during the global recession when industrial production and tranportion were low. As you can see, as it's recovered it has increased even more steeply than before, back towards the worst case scenario model.
Dr. L. Rasmussen
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