Global warming simulations suggest that wet regions (where precipitation exceeds evaporation) will become wetter and dry regions drier by the end of the 21st century (e.g., Held and Soden 2006), with larger contrasts expected between dry and wet seasons (Chou et al., 2013). This ‘rich-get-richer’ behavior is consistent with a large increase in the moisture content of atmosphere, leading to enhanced horizontal moisture fluxes across regions.
(CNN) Most of us can appreciate that the world is an ancient place and that a lot has changed in the almost 4.6 billion years since it took its shape.
It’s not easy to have a feel for the amount of time that has passed, but grappling with deep time helps you understand why an atmospheric carbon dioxide concentration (CO2) of 400 parts per million (ppm) is meaningful.
Deep time is geologic time and the scale needed to fathom the evolution of life, mountains, oceans, and Earth’s climate.
Subpolar ocean gyres (large systems of rotating ocean currents) in the Southern Hemisphere are found poleward of the Antarctic Circumpolar Current near the Weddell and Ross Sea. They play a key role in the global energy and water budgets. These gyres are crucial for the transport of heat around the planet, as well as the distribution of nutrients and marine species. Thus, the subpolar gyres are important in the mixing and transformation of water masses.
We are currently on the eve of a world with ~400 parts per million (ppm) of atmospheric carbon dioxide (398.35 ppm as of May 2nd, Mauna Loa Observatory). How global climate, sea-level and ecosystems will respond to this level of CO2 level is a key question for global change research. Recently, Foster and Rohling (2013) looked back into Earth’s geological history to explore the relationship between atmospheric CO2 and global sea-level.
Earth’s climate is characterized by persistent westerly jets (eastward flow) in the upper troposphere, located in the mid-latitudes of the Northern and Southern Hemisphere, which are associated locally with strong weather systems. The location of these jets is of paramount importance to human societies, as these are collocated with maximum in precipitation rates and surface winds in the extratropical regions.
In their recent Science article, Marcott and colleagues present a reconstruction of Earth’s mean surface temperature over the last 11,300 years – the Holocene. Why is this important? It is the most comprehensive and inclusive reconstruction to date from which to assess how novel our current temperatures are compared with those in the recent geologic past. In other words, are we experiencing average temperatures that are essentially unprecedented over this timeframe?
Respiration by plants and microorganisms is primarily responsible for mediating carbon exchanges between the biosphere and atmosphere. Climate warming has the potential to influence the activity of these organisms, altering the exchanges between carbon pools. Traditionally, the respiratory release of CO2 into the atmosphere is thought to be more temperature-sensitive than photosynthesis (carbon fixation), generating a positive climate-ecosystem carbon feedback with the potential to accelerate climate warming by up to 1.4 times.
Earth’s climate system includes several patterns of climate variability at the hemispheric scale. One of the best known of these is the El-Nino/Southern Oscillation, which influences weather across much of the globe. Another important feature of the climate system is the Southern Annular Mode (also known as the Antarctic Ocean Oscillation), which is an index of the pressure gradient between the mid- and high-latitudes in the Southern Hemisphere. Over the last few decades, the dominance of the positive phase of the Southern Annular Mode has been increasing.
Methane, a greenhouse gas second in importance only to carbon dioxide, has built up rapidly in the atmosphere since the Industrial Revolution due to human emissions. It was believed that prior to the 19th century,