The Transcendent Threat: Climate Trends

An introduction to climate trends and consequences

We have sought to use a "climate art" approach to introduce some key climate-related trends, supplemented by short text that serves to lead a reader into the more technical literature. Often our first suggested link into that literature is to a New York Times article or other piece written for the general reader. While these articles do not satisfy the definition of "technical" by the standard of any working scientist, they invariably do list names of researchers that you could use in a database search to learn more. This introduction to climate trends and consequences is a dynamic effort, and we welcome comments at This e-mail address is being protected from spambots. You need JavaScript enabled to view it . We invite you to read more about The Transcendent Threat: Climate Trends.

The Keeling Curve

To the right is a famous curve in climate science, now known as the “Keeling Curve." For most of the industrial revolution, coal and other fossil fuels were burned but the fate of the resulting carbon dioxide was a matter of speculation. The invisible became visible starting in 1958, when Charles David Keeling (1928-2005) began measuring carbon dioxide in the air over Hawaii. By the third year of work, Keeling had proved to his peers’ satisfaction that this greenhouse gas varied seasonally, but more importantly was on a relentless trajectory upward. Measurements continue to this day, on Hawaii and at many other locations.

The Hockey Stick

This is a second iconic curve, the “hockey stick." Note that the Y axis is of change, not of simple temperature. The zero line represents an agreed-upon “baseline” and the choice of this baseline is somewhat arbitrary since the point is to look at change over time. What the numerous colored curves show is that by various “proxy” measures of past temperatures (marine sediments, ice cores, tree rings, etc.), average global temperatures have been cooler than they are today, for many hundreds of years into the past. Warming coincides with the start of the industrial revolution. For further discussion of this curve see http://www.agu.org/sci_soc/prrl/prrl0319.html
 

Seas on the Rise

Sea level records from 23 “geologically stable” coastal sites were gathered by Bruce Douglas in a 1997 study, that resulted in this collection of curves.  The black line is the average, the thick red line adds in recent data from a satellite.  The two data sources are in agreement that average sea levels are on the rise.  Sea level rises for two reasons - 1) as water warms it expands slightly and 2) as glaciers melt they add their water to the sea.  A recent report found that ocean temperatures this past summer (2009) were the warmest on record (since 1880), see http://www.noaanews.noaa.gov/stories2009/20090916_globalstats.html

State of the Arctic

The coverage of arctic sea ice in the summer months has been steadily dwindling. The relentless downward trend finally ended in 2009, when a relatively cool summer held sea ice to a higher level than the previous year.  Nevertheless the long term trend is shown clearly in a graph in this NY Times piece, see chart starting in 1978 here. Most scientists expect that 2009 will provide only a temporary reprieve, given the rise in sea level temperatures generally.

Flooding

Flooding can be expected to increase for two reasons. First, for coastal areas, any increase in sea level will increase the flooding potential during major storm events. Hurricanes and other major storms create a “storm surge” of water ahead of them, so that when they make landfall the sea can flood inland. Logically,  if the baseline of normal sea level near a city increases, the storm surge will start at a higher level, increasing its potential reach. And as shown elsewhere in this slide show, sea level is increasing, on average. Second, for inland regions flooding will increase if rainfall events deliver more water in sudden downpour fashion. This change in rainfall has been observed for several regions around the world, see it here.

 Follow the Bark Beetles

There is some debate over the cause of massive outbreaks of bark beetles, and their movement into more northern regions of North American than normal. Nevertheless there does appear to be a general consensus that warmer winters are a factor allowing the beetles to thrive, and there is a stronger still consensus that the northern expansion of the beetles (e.g., into northern Alberta where they have not been seen before) is related to climate. Dry summers are also a factor, because trees attacked by beetles produce a resin in an effort to entomb them, but cannot produce resin in good quantity during dry weather. Click here for an overview of this issue.

In Full Bloom

Scores of articles in recent years have documented changes in phenology, especially an earlier arrival of spring events. Phenology is the study of the timing of bloom time, bird migration, crop maturation, and other events in nature. The longest detailed phenological record in all the world is available in Japan, recording the blooming time of cherry blossoms since the 9th century. On average, cherry trees are blooming about four days earlier than ever before recorded, and up to eight days earlier in cities. Results vary some by species. (See Primack RB, Higuchi H, Miller-Rushing AJ, 2009. The impact of climate change on cherry trees and other species in Japan.  Biological Conservation 142: 1943 – 1949.) This article also lists dozens of papers about other phenological events, and is therefore an excellent lead into this large literature. (For cherry blossom studies in particular, that tease apart the “urban heat island” effect from overall regional warming, see Aono, Y., Kazui, K., 2008. Phenological data series of cherry tree flowering in Kyoto, Japan, and its application to reconstruction of springtime temperatures since the 9th century. International Journal of Climatology 28, 905–914.)

Hurricanes

Hurricane Katrina was among the strongest hurricanes ever to strike the U.S. according to scientists at the NOAA National Climatic Data Center in Asheville, N.C. Read more here.

Coral bleaching

Coral bleaching risk is up in Summer 2009. Read more about it here and here.

Political Will

On Friday, 26 June 2009, for the first time in its history, the US Congress successfully passed legislation placing a price on carbon dioxide. The Waxman-Markey bill passed by a narrow margin and largely along party lines. The Senate must now take up the measure, and debate is expected to be sharp. The House bill would allocate and eventually auction emission permits to major sources of greenhouse gases such as power plants, and would raise billions of dollars that to be used for energy efficiency and renewable energy projects, potentially creating many jobs. The estimated cost per household of approximate $150 per year in higher energy bills will be partly offset for low income households with a tax offset of $40. To see how your representative voted click here.

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