AGW Observer

Observations of anthropogenic global warming

Archive for July, 2009

Papers on Biological Indicators of Global Warming

Posted by Ari Jokimäki on July 31, 2009

This list of papers contains evidence of various types of biosphere reactions to the global warming. However, the temperature reconstructions from tree rings, corals, etc. are not included to this list. The list is not complete (and will not be as there so much papers on this subject), and will most likely be regularily updated in the future in order to make it more thorough and more representative.

NOTE! See also this more thorough list of papers in uknowispeaksense.

UPDATE (February 19, 2011): Thackeray et al. (2010) added. Thanks to Chris S. for pointing it out, see the comment section.
UPDATE (August 2, 2010): Boyce et al. (2010) added.
UPDATE (December 5, 2009): Williamson et al. (2009) added, thanks to Paul Middents for pointing it out, see the comment section.
UPDATE (December 4, 2009): Kannan & James (2009) added.
UPDATE (September 17, 2009): Hughes (2000) and Root et al. (2003) added.

Trophic level asynchrony in rates of phenological change for marine, freshwater and terrestrial environments – Thackeray et al. (2010) “Recent changes in the seasonal timing (phenology) of familiar biological events have been one of the most conspicuous signs of climate change. However, the lack of a standardized approach to analysing change has hampered assessment of consistency in such changes among different taxa and trophic levels and across freshwater, terrestrial and marine environments. We present a standardized assessment of 25 532 rates of phenological change for 726 UK terrestrial, freshwater and marine taxa. The majority of spring and summer events have advanced, and more rapidly than previously documented. Such consistency is indicative of shared large scale drivers. Furthermore, average rates of change have accelerated in a way that is consistent with observed warming trends. Less coherent patterns in some groups of organisms point to the agency of more local scale processes and multiple drivers. For the first time we show a broad scale signal of differential phenological change among trophic levels; across environments advances in timing were slowest for secondary consumers, thus heightening the potential risk of temporal mismatch in key trophic interactions. If current patterns and rates of phenological change are indicative of future trends, future climate warming may exacerbate trophic mismatching, further disrupting the functioning, persistence and resilience of many ecosystems and having a major impact on ecosystem services.” Stephen J. Thackeray, Timothy H. Sparks, Morten Frederiksen, Sarah Burthe, Philip J. Bacon, James R. Bell, Marc S. Botham, Tom M. Brereton, Paul W. Bright, Laurence Carvalho, Tim Clutton-Brock, Alistair Dawson, Martin Edwards, J. Malcolm Elliott, Richard Harrington, David Johns, Ian D. Jones, James T. Jones, David I. Leech, David B. Roy, W. Andy Scott, Matt Smith, Richard J. Smithers, Ian J. Winfield, Sarah Wanless, Global Change Biology, Volume 16, Issue 12, pages 3304–3313, December 2010, DOI: 10.1111/j.1365-2486.2010.02165.x. [Full text]

Global phytoplankton decline over the past century – Boyce et al. (2010) “In the oceans, ubiquitous microscopic phototrophs (phytoplankton) account for approximately half the production of organic matter on Earth. Analyses of satellite-derived phytoplankton concentration (available since 1979) have suggested decadal-scale fluctuations linked to climate forcing, but the length of this record is insufficient to resolve longer-term trends. Here we combine available ocean transparency measurements and in situ chlorophyll observations to estimate the time dependence of phytoplankton biomass at local, regional and global scales since 1899. We observe declines in eight out of ten ocean regions, and estimate a global rate of decline of ~1% of the global median per year. Our analyses further reveal interannual to decadal phytoplankton fluctuations superimposed on long-term trends. These fluctuations are strongly correlated with basin-scale climate indices, whereas long-term declining trends are related to increasing sea surface temperatures. We conclude that global phytoplankton concentration has declined over the past century; this decline will need to be considered in future studies of marine ecosystems, geochemical cycling, ocean circulation and fisheries.” [Full text]

L&O special issue: Lakes and Reservoirs as Sentinels, Integrators, and Regulators of Climate Change – Williamson et al. (2009) Lot of relevant articles, many of them with free access to the full text.

Effects of climate change on global biodiversity: a review of key literature – Kannan & James (2009) A review article. “After a brief overview of climate change and its causes, focus is given to amphibian extinctions in Central America, the poleward and altitudinal shifts in the distribution of various organisms (especially butterflies), the spread of pathogen-driven diseases, the bleaching of coral reefs, and the changes in community and trophic dynamics in various marine and terrestrial ecosystems.” [Full text]

Attributing physical and biological impacts to anthropogenic climate change – Rosenzweig et al. (2008) “Here we show that these changes in natural systems since at least 1970 are occurring in regions of observed temperature increases, and that these temperature increases at continental scales cannot be explained by natural climate variations alone.”

Rapid shifts in plant distribution with recent climate change – Kelly & Goulden (2008) “We compared surveys of plant cover that were made in 1977 and 2006–2007 along a 2,314-m elevation gradient in Southern California’s Santa Rosa Mountains. … We found that the average elevation of the dominant plant species rose by 65 m between the surveys. This shift cannot be attributed to changes in air pollution or fire frequency and appears to be a consequence of changes in regional climate.” [Full text]

Net carbon dioxide losses of northern ecosystems in response to autumn warming – Piao et al. (2008) “We find that both photosynthesis and respiration increase during autumn warming, but the increase in respiration is greater. In contrast, warming increases photosynthesis more than respiration in spring. Our simulations and observations indicate that northern terrestrial ecosystems may currently lose carbon dioxide in response to autumn warming, with a sensitivity of about 0.2 PgC °C-1, offsetting 90% of the increased carbon dioxide uptake during spring. If future autumn warming occurs at a faster rate than in spring, the ability of northern ecosystems to sequester carbon may be diminished earlier than previously suggested” [Full text]

Impact of global warming on a group of related species and their hybrids: cherry tree (Rosaceae) flowering at Mt. Takao, Japan – Miller-Rushing et al. (2007) “The cherry trees flowered earlier over time, by an average of 5.5 d over the 25-yr study. Earlier flowering was explained largely by a 1.8°C increase in February–March mean monthly temperatures. Most species and hybrids flowered 3–5 d earlier for each 1°C increase in temperature, but early-flowering taxa flowered as much as 9 d earlier for each 1°C increase in temperature.” [Full text]

Influences of species, latitudes and methodologies on estimates of phenological response to global warming – Parmesan (2007) “Analyses here on a new expanded dataset estimate an overall spring advancement across the northern hemisphere of 2.8 days decade−1.” [Full text]

Rapid advancement of spring in the High Arctic – Høye et al. (2007) “Using the most comprehensive data set available from this region, we document extremely rapid climate-induced advancement of flowering, emergence and egg-laying in a wide array of species in a high-arctic ecosystem. The strong responses and the large variability within species and taxa illustrate how easily biological interactions may be disrupted by abiotic forcing, and how dramatic responses to climatic changes can be for arctic ecosystems.”

Escaping the heat: range shifts of reef coral taxa in coastal Western Australia – Greenstein & Pandolf (2007) “Coral taxa present in modern communities clearly expanded and contracted their geographic ranges in response to climate change.”

Human Contribution to the Lengthening of the Growing Season during 1950–99 – Christidis et al. (2007) “The [increase in the growing season length] signal is found to be detectable, both on global and continental scales, and human influence needs to be accounted for if it is to be fully explained.”

European phenological response to climate change matches the warming pattern – Menzel et al. (2006) “Our analysis of 254 mean national time series undoubtedly demonstrates that species’ phenology is responsive to temperature of the preceding months (mean advance of spring/summer by 2.5 days°C−1, delay of leaf colouring and fall by 1.0 day°C−1). The pattern of observed change in spring efficiently matches measured national warming across 19 European countries (correlation coefficient r=−0.69, P<0.001)." [Full text]

Climate change and population declines in a long-distance migratory bird – Both et al. (2006) Studies the mistiming between a bird nesting and it’s food species abundance caused by climate change. “Mistiming as a result of climate change is probably a widespread phenomenon, and here we provide evidence that it can lead to population declines.” [Full text]

Global Genetic Change Tracks Global Climate Warming in Drosophila subobscura – Balanyá et al. (2006) “In 22 of 26 populations, climates warmed over the intervals, and genotypes characteristic of low latitudes (warm climates) increased in frequency in 21 of those 22 populations. Thus, genetic change in this fly is tracking climate warming and is doing so globally.” [Full text]

Ecological and Evolutionary Responses to Recent Climate Change – Parmesan (2006) A review article. “These observed changes are heavily biased in the directions predicted from global warming and have been linked to local or regional climate change through correlations between climate and biological variation, field and laboratory experiments, and physiological research.” [Full text]

Fingerprints of global warming on wild animals and plants – Root et al. (2003) “We gathered information on species and global warming from 143 studies for our meta-analyses. These analyses reveal a consistent temperature-related shift, or ‘fingerprint’, in species ranging from molluscs to mammals and from grasses to trees. Indeed, more than 80% of the species that show changes are shifting in the direction expected on the basis of known physiological constraints of species.”

A globally coherent fingerprint of climate change impacts across natural systems – Parmesan & Yohe (2003) Studies the range shifts of species. “This suite of analyses generates ‘very high confidence’ (as laid down by the IPCC) that climate change is already affecting living systems.” [Full text]

Biological consequences of global warming: is the signal already apparent? – Hughes (2000) “Increasing greenhouse gas concentrations are expected to have significant impacts on the world’s climate on a timescale of decades to centuries. Evidence from long-term monitoring studies is now accumulating and suggests that the climate of the past few decades is anomalous compared with past climate variation, and that recent climatic and atmospheric trends are already affecting species physiology, distribution and phenology.”


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THE argument

Posted by Ari Jokimäki on July 30, 2009


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Introduction to the Observations of Anthropogenic Global Warming

Posted by Ari Jokimäki on July 28, 2009

The theories on AGW (and the details of climate models) are based on huge amount of observations made in laboratories and in field (in atmosphere, oceans, land, space). The history of the subject is given in “The Discovery of Global Warming” by Spencer Weart. Links to the basics of the subject are given in this RealClimate article.

Observational side of the subject starts with laboratory measurements of the basic properties of so called greenhouse gases (GHG). Especially relevant are the infrared absorption properties of the molecules of GHG’s because it is the infrared radiation that GHG’s absorb in the atmosphere to create the greenhouse effect. There are hundreds, or more likely thousands, of studies made starting from 1850’s studying the infrared properties of the GHG’s. In a very basic level, the laboratory studies are done so that infrared radiation is directed through a concentration of certain gas, and then it is measured how much infrared radiation comes out to see if the gas is absorbing some of the radiation. There are lot of variations of this basic setup in different studies; some use different temperature, pressure, gas concentration, spectral range, and so on.

In addition to measuring the basic properties of the GHG molecules in laboratories, we have made lot of observational work of their properties in actual atmosphere. Our basic site for measurements is of course Earth’s atmosphere, but we have done lot of measurements of the atmospheres of other planets also (most relevant to the subject here are probably Venus’ and Mars’ atmospheres). Earth’s atmospheric measurements have been done by using airplanes, balloons, and satellites to take necessary instruments high in the atmosphere (or outside of it), and some measurements can be done on ground. These measurements have shown that greenhouse gases work in the atmosphere pretty much like we expect based on the laboratory measurements. Currently, we already have almost direct measurements of the warming caused by greenhouse gases. We also know from the observations that CO2 concentrations are rising in the atmosphere, and that the reason for the rising concentration is emissions from human activities (this can be deduced by measuring the fractions of certain carbon isotopes in atmosphere).

Further support for direct laboratory and atmospheric measurements of greenhouse gas effects comes from paleoclimatic records. There are some places where information of past climatic conditions can be found. Ice cores for example are one such place (there are many others as well). When more ice is created, some air bubbles are trapped within the ice. Those air bubbles therefore contain the air from the atmosphere as it was when the ice was created, and we can measure for example CO2 concentration from them. The ice cores drilled from the Antarctic for example contain air bubbles with atmospheric information reaching back hundreds of thousands of years. These records of past climate have teached us that greenhouse gases have had a strong effect to past climate.

From other perspective, for a long time we have kept temperature measurement records. Those records show that most of the 20th century Earth’s surface was getting warmer, just as would be expected if greenhouse gas concentrations would rise. Supporting that, we have lot of indirect methods to determine temperature. These have caused lot of debate, especially tree rings. There are also signals of warming, such as glacier melting and different effects in ecosystem (spring activity occurring earlier for example). Ocean temperatures have also been measured for a long time, and anthropogenic global warming signal has been found from the global ocean too.

We also do lot of measurements of the Sun, clouds, rain, volcanoes, ocean currents, wind, snow cover, and all such things that can have an effect to the weather and climate. There are also some special observations. Fossilized plants exposed by melting glaciers for example tell us that the current temperature is higher than it has been for thousands of years. All in all, the whole issue is very well covered by observations alone.

Later, I will be making more detailed entries on the issues discussed above (with decent references too), but for now I just leave you with this introduction to the subject.

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AGW Observer

Posted by Ari Jokimäki on July 28, 2009

Hi and welcome to AGW Observer!

This blog is about climate science with an emphasis on the observations of the climate change that is currently ongoing. Specifically the emphasis will be on those observations that show that it is mankind that is and has been causing this current climate change by greenhouse gas emissions. The AGW in the title stands for Anthropogenic Global Warming, which is a commonly used term for the current human-caused climate change.

I am not a professional climate scientist, but just an interested layman who has been getting familiar particularly to the observational side of the issue by reading the research papers on the subject. I hope I can offer some relevant information on the subject especially as the public discussion on the subject tends to focus more on what climate models can do instead of emphasizing the observational body of evidence which is very large and in my opinion convincing by itself even without far-reaching climate theories or models.

Have fun.

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