Two years ago I made a post that featured a dozen or so maps and graphs that lended insight into global warming. It turned out to be one of the most read pages on my site. I now want to update that page with even better and a larger number images which are relevant to climate change. They will feature only very brief explanations. Most of what is being shown is self-evident, but if you have questions, feel free to ask them. Hopefully this can serve as a good reference for those who want some images relevant to global warming. I also recommend the site http://www.globalwarmingart.com. These images can all be clicked on for enhanced view. I am also happy to take further suggestions and them.
The global climate system is ultimately driven by the radiative balance at the top of the atmosphere and surface energy budget terms. Heat flows from the warm surface to the cold atmosphere and from the warm tropics to the cold equator to help eliminate the gradients that would be produced by radiation alone. The first image below shows the globally and annually averaged heat fluxes. The second shows the latitudinal distribution of solar and terrestrial heat fluxes.
Trenberth et al 2009
For understanding the greenhouse effect (see here) we’re interested in the ability of various atmospheric gases to retard the outgoing infrared energy exiting the planet. We can see how these gases takes “bites” out of the outgoing spectrum (this is upwelling infrared, as would be seen for example by a viewer from space) and thus makes the planet a less effective emitter at a given temperature. We can also look at transmittance, which is essentially one in”atmosphere windows” or zero in strongly absorbing regions.
We can look at the same effect in terms of “brightness temperature.” This is an inverted form of the Planck law. It is noteworthy that in regions where gases do not really absorb strongly (say, 8-12 microns) that a viewer looking from space would see radiation coming from the surface, at the hot temperature of the surface (close to 290 K). In strongly absorbing regions, a viewer from space does not need to look very far down and will see radiation emanating from higher, colder parts of the atmosphere.
Of prime importance to us is increases in global temperature. A fairly standard time-series showing the evolution of temperature anomalies (i.e., the departure from some arbitrary mean value, in this case the 1951-80 climatology) is:
This can be decomposed into hemispheric contributions, as seen below:
These images were obtained from the NASA GISTEMP page, as are some sample outputs produced below, which show a global map of temperature anomalies so that one can see the zonal and meridional structure of global warming.
This plot is for 1995-2009 anomalies relative to the 1951-1980 mean.
And a 2000-2009 anomaly map
In understanding this temperature rise, we are interested in the radiative forcing of various agents, such as fluctuations in greenhouse gases, anthropogenic aerosols, solar flux, and volcanoes. Radiative forcing is a useful tool to compare the influence of different things on a side-by-side basis:
Positive forcing indicate warming influences, and negative forcings, cooling influences. More detail here. As we can see, aerosols have done a considerable job at offsetting greenhouse warming, but they also have a lot more uncertainty associated with them. There are some examples of the global distribution of radiative forcing. For instance, a model output of the RF from CO2 from 1880-2000 reveals that the RF is not completely uniform over the globe
This is a result of the increase in CO2 over industrial time, plotted below
There is a very clear upward trend in CO2, as well as a beautiful annual cycle associated with the disproportionate vegetation responses between hemispheres over a year. We can see a human-induced fingerprint in the rise of atmospheric CO2 by looking at the decline of oxygen, which is a result of combustion, as well as a decline in C13/C12 ratio which is consistent with burning fossil fuels:
To-date and projections of future CO2 emissions are below in GtC yr-1. We are currently tracking on the high end of various economic scenarios:
Copenhagen report, 2009
pCO2 can be reconstructed from the trapped air in the bubbles of ice cores in Antarctica (they do not currently use Greenland for CO2, maybe some hope in the future), but the longest record in ice cores can go back 800,000 years.
Luthi et al 2008, Nature
Currently, CO2 concentratios are at 390 ppm, much higher than at any time in that record. This can also be put into the context of radiative forcing over long periods of time. For example, this plot shows the evolution of concentrations and the RF from CO2, methane, and nitrous oxide over the last 20,000 years.
Joos and Spahni, 2008, PNAS
Over the last 400,000 years, we can look at the evolution of concentrations and forcing, as well as sea level.
Hansen et al 2008
Here is the CLIMAP reconstruction of surface conditions of the LGM oceans relative to modern SST’s.
This plot is current best estimates of Northern Hemisphere temperatures over the last few millennia,
Mann et al 2008
The sea level rise over the last few decades is also large, coming in at over 3 mm yr-1. Here is a plot showing a recent time-series of sea-level rise with the seasonal cycle removed
As we’ve seen, greenhouse gases are the largest radiative forcing agent since pre-industrial time. Other things do matter though, and studying them is important. Here is a plot of solar intensity over the last few decades:
There has been essentially no secular trend in solar irradiance over this time, although there is a clear ~11-year cycle.
This is an interesting figure showing the amount of CO2 taken up by the oceans to 1994. The interesting thing to note is the North Atlantic, which represents a relatively small area of the global ocean, has taken up a disproportionately large amount of carbon (25% of inventory with 15% of area)
We can also get a feel for the penetration depth of CO2 in the ocean. Because the ocean mixes slowly, most of the CO2 is in a relatively shallow region. The deep mixing in the North Atlantic, which explains the phenomena is the preceding figure, is evident here:
Mauri Pelto has suggested some of these images of glacier mass balance over time:
The rest of these images I just have for making them clickable somewhere else, sorry for lack of descriptions
These following graphs have no physical significance…I’m placing them here for a bookmark only, do not cite: