Saturday, July 18, 2015

The Future of Earth - By Fire


Will it be by fire or by ice that Earth will meet its end? Well it all depends on how you define "end". It has been known for quite some time that eventually the Earth will be swallowed by an expanding sun when the sun reaches its final stages of life as a red giant. This stage will begin sometime between 5 and 7 billion years from now - here is a nice video giving some great visualizations of what we think will happen. But a recent article in the Journal of Geophysical Research - Atmosphere tells us that we'll have our last best day far sooner. 

The sun is getting brighter (see footnote 1). One of the early challenges for paleoclimatologists (people who study the climates of yesteryear) was understanding the evolution of sun like stars and its impact on climate early in life's history on Earth. In a recent article in the journal JGR-Atmospheres authors Wolf and Toon found that increasing solar luminosity will make the Earth uninhabitable in about 2 billion years (time to start planning folks!). The good news is that though life won't be able to survive, the planet is unlikely to experience a runaway greenhouse effect as may have been the case of Venus.

Somewhat more seriously it is not that clear in my skimming the article (apologies if it is covered - time constraints) if surface albedo might influence the evolution of Earth's climate under a brightening sun. Here is where we find the theories of James Lovelock and the Gaia Hypothesis




1 From Paleoclimate Implications for Human-Made Climate Change (pdf)
James E. Hansen and Makiko Sato
http://www.columbia.edu/~jeh1/mailings/2011/20110118_MilankovicPaper.pdf


Solar luminosity is increasing on long time scales, as our sun is at an early stage of solar evolution, "burning" hydrogen, forming helium by nuclear fusion, slowly getting brighter. The sun's brightness increased steadily through the Cenozoic, by about 0.4 percent according to solar
physics models (Sackmann et al., 1993). 


Urban Climate

A recent journal article by MZ Jacobson et al points out some of the climatological impacts of urbanization on local climate. The land use change that urbanization leads to is known to impact climatological conditions through changes in soil moisture evaporation, transpiration (evaporation from plants), heat absorption and advection (wind).

In this article the authors used models to study the impact of the change in urban extent in Beijing. Beijing provides a good case due to the extreme nature of changes there - the urban extent of the city quadrupled between 2000 and 2009.

Key Points from the article:

  • Beijing's expansion created a ring of impact in the new portion of the city
  • Without considering the impact of more vehicles and other sources of human caused polution - urbanization's impact on climatological conditions alone slowed winds and increased pollution vertical dilution and increased ground level temperature, and ozone

Interestingly the authors used crowdsourced data on road surface area in their study.

Take homes:
This study found that urbanization changes local climate in these ways - it:

  • increases ground level temperature
  • decreases ground level humidity
  • decreases horizontal movement of air (wind, advection)
  • increases vertical movement of air (convection)
  • reduces reflectivity of the surface (albedo) causing the retention of more solar energy
These impacts:

  • decreased surface pollution by promoting vertical mixing
  • but increased surface ozone (O3) due to other changes in the chemical profile of the air
None of these impacts takes into account vehicle use or other pollution sources.


Mark Z. Jacobson, Son V. Nghiem, Alessandro Sorichetta and Natasha Whitney
Article first published online: 19 JUN 2015 | DOI: 10.1002/2014JD023008

Saturday, February 16, 2013

Resilience - what it is, and what it could be.

What is resilience and how do you put that into practice? Here are links to three publications that speak to resilience in the context of addressing climate change in cities and what it means in terms of planning and implementation. Resilience is not just "getting back on one's feet and returning to what you had before" but rather an opportunity for fundamental change - or to use the current buss phrase, an opportunity for transformation.



Link to PDF File

The term resilience is increasingly applied in thinking through how to deal with climate change. On one level it can be applied as a way of bridging the historic al divide that has existed between climate mitigation and climate adaptation. Climate resilience refers to both actions that reduce climate impacts as well as actions to respond to climate impacts. Resilience can be seen as a process of learning and innovation—we can always be more resilient. 

There are different definitions of resilience in various disciplines. Reviewing the way s in which the term resilience has been defined is useful for understanding the challenge of dealing with climate change. 

Importantly both of the definitions provided on the facing page emphasize the capabilities to learn and anticipate, as well as to respond to change. 





Abstract

Climate change will have unavoidable impacts on urban systems and populations, especially in Asia where many large cities are exposed. Climate adaptation will be essential, and planning for adaptation can be simplified through operationalizing concepts of climate resilience and vulnerability. This article reviews concepts and theories in a range of diverse fields to illustrate how the general notion of urban climate resilience can be developed into an operational framework for planning practitioners. The framework integrates theoretical and empirical knowledge of the factors contributing to resilience with processes for translating those concepts into practice. The framework includes characteristics of urban systems, the agents (people and organizations) that depend on and manage those systems, institutions that link systems and agents, and patterns of exposure to climate change. It operationalizes these concepts through structured and iterative shared learning approaches that allow local planners to define these factors in their own context, in order to develop practical strategies for local action. The viability of the framework is demonstrated through examples from resilience planning activities undertaken in 10 cities across Asia through the Asian Cities Climate Change Resilience Network funded by the Rockefeller Foundation.


Sunday, June 1, 2008

A New World Water Power?

At least that's what the University of Waterloo thinks...

http://www.bulletin.uwaterloo.ca/2008/may/30fr.html

UW could lead the world in water

Waterloo “may be the best positioned” university in North America, perhaps in the world, to be “the leading centre in water research”, says a report that’s being made public this week by UW’s provost.



Wednesday, September 12, 2007

Palaeozoic CO2 and Temperature: coupled again?

Though there are many other influences on climate such as contintental
configuration that can change over the period of hundreds of millions
of years, GHGs are still considered an primary driver of average
surface temperature. Which is why the publication by Veizer et al in
2000 (ref 4 in abstract below) of a sea surface reconstruction of
temperatures from the Palaeozoic era had led to some confusion. What
they had found was that during a period of high CO2 the sea surface
temperature had not been greatly affected. Or, there had been a
decoupling of CO2 and temperature. In today's Nature a new
reconstruction has been presented that uses a different proxy method
and finds sea surface was indeed much warmer during high CO2 periods
than during low CO2 periods. This then throws into question CO2
decoupling during the Palaeozoic era.



http://www.nature.com/nature/journal/v449/n7159/abs/nature06085.html

Nature 449, 198-201 (13 September 2007) | doi:10.1038/nature06085;
Received 15 April 2007; Accepted 3 July 2007

Coupling of surface temperatures and atmospheric CO2 concentrations
during the Palaeozoic era

Rosemarie E. Came1, John M. Eiler1, Ján Veizer2, Karem Azmy3, Uwe
Brand4 & Christopher R. Weidman5


Atmospheric carbon dioxide concentrations seem to have been several
times modern levels during much of the Palaeozoic era (543–248 million
years ago), but decreased during the Carboniferous period to
concentrations similar to that of today1, 2, 3. Given that carbon
dioxide is a greenhouse gas, it has been proposed that surface
temperatures were significantly higher during the earlier portions of
the Palaeozoic era1. A reconstruction of tropical sea surface
temperatures based on the delta18O of carbonate fossils indicates,
however, that the magnitude of temperature variability throughout this
period was small4, suggesting that global climate may be independent
of variations in atmospheric carbon dioxide concentration. Here we
present estimates of sea surface temperatures that were obtained from
fossil brachiopod and mollusc shells using the 'carbonate clumped
isotope' method5—an approach that, unlike the delta18O method, does
not require independent estimates of the isotopic composition of the
Palaeozoic ocean. Our results indicate that tropical sea surface
temperatures were significantly higher than today during the Early
Silurian period (443–423 Myr ago), when carbon dioxide concentrations
are thought to have been relatively high, and were broadly similar to
today during the Late Carboniferous period (314–300 Myr ago), when
carbon dioxide concentrations are thought to have been similar to the
present-day value. Our results are consistent with the proposal that
increased atmospheric carbon dioxide concentrations drive or amplify
increased global temperatures1, 6.

Tuesday, September 11, 2007

Land use change and global warming

An interesting tidbit that showed up over at Nature's "Nature Reports: Climate Change" in a story on what might be the discovery of the missing carbon sink.

Albedo effect


Other scientists have also recently come to the conclusion that northern forests, although critically important in maintaining biodiversity, might be less important in slowing climate change than tropical forests. Govindasamy Bala and Ken Caldeira found that tropical forests help cool the Earth in two ways: by storing carbon and also by reflecting the suns warming rays back to space5. "Unlike tropical forests, high latitude forests darken the Earth's surface, causing the earth to absorb more sunlight, an effect that is most pronounced in snowy regions. This darkening of the surface has a warming influence that can be stronger than the cooling influence of carbon storage in these forests," says Caldeira. This suggests that removing high-latitude forests would have a net cooling effect on the planet, whereas removal of tropical forests would result in warming.

What is interesting here is what has been happening for the past 30 to 50 years. Northern forests have been growing and tropical forests have been shrinking. Thus, according to the above, this should lead to warming. How much of this land use change impact is included in the models of climate change? Not sure.

Friday, August 10, 2007

New Model: Some near term offset of anthropogenic warming


A new model, published in Science, that includes more information about the internal variability of the Earth system (e.g. El Ninos, etc.) predicts some potential for ameliorating anthropogenic warming in the next tens years (yet about 50% of the years after 2009 are still predicted to be warmer than 1998 (the warmest so far)).

___

Science 10 August 2007:

Vol. 317. no. 5839, pp. 796 - 799
DOI: 10.1126/science.1139540

Improved Surface Temperature Prediction for the Coming Decade from a Global Climate Model
Doug M. Smith,* Stephen Cusack, Andrew W. Colman, Chris K. Folland, Glen R. Harris, James M. Murphy

Previous climate model projections of climate change accounted for
external forcing from natural and anthropogenic sources but did not
attempt to predict internally generated natural variability. We
present a new modeling system that predicts both internal variability
and externally forced changes and hence forecasts surface temperature
with substantially improved skill throughout a decade, both globally
and in many regions. Our system predicts that internal variability
will partially offset the anthropogenic global warming signal for the
next few years. However, climate will continue to warm, with at least
half of the years after 2009 predicted to exceed the warmest year
currently on record.

Figure 4
Fig. 4. Globally averaged annual mean surface temperature
anomaly (relative to 1979–2001) forecast by DePreSys starting from June
2005. The CI (red shading) is diagnosed from the standard deviation of
the DePreSys ensemble, assuming a t distribution centered on
the ensemble mean (white curve). Also shown are DePreSys and ensemble
mean NoAssim (blue curves) hindcasts starting from June 1985 and June
1995, together with observations from HadCRUT2vOA (black curve).
Rolling annual mean values are plotted seasonally from March, June,
September, and December. The mean bias as a function of lead time was
computed from those DePreSys hindcasts that were unaffected by Mount
Pinatubo (SOM text) and removed from the DePreSys forecast (but not the
hindcasts).



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