Sentences with phrase «in ice sheet albedo»

In their latest Science paper submittal Jim Hansen, et al. argue that we must reduce atmospheric CO2 to below 350 ppm because so - called «slow feedbacks» such as changes in ice sheet albedo are occurring much faster than expected.

Not exact matches

What G&T are missing is the linear effect of water vapour accelerating the ice albedo effect of change in size of the sea ice sheets.

This mitigates the albedo feedback, as does the lowering in sea level that accompanies the formation of ice sheets.

The importance of orbital variations, of the greenhouse gases CO2, CH4 and N2O, of the albedo of land ice sheets, annual mean snow cover, sea ice area and vegetation, and of the radiative perturbation of mineral dust in the atmosphere are investigated.

On the studies of sensitivity based on the last glacial maximum, what reduction in solar forcing is used based on the increased Albedo of the ice - sheets, snow and desert.

26 Paul W asked, «On the studies of sensitivity based on the last glacial maximum, what reduction in solar forcing is used based on the increased Albedo of the ice - sheets, snow and desert.

How the albedo of the Greenland ice sheet in July 2017 compared to the average for July from 2000 - 2009.

Other factors would include: — albedo shifts (both from ice > water, and from increased biological activity, and from edge melt revealing more land, and from more old dust coming to the surface...); — direct effect of CO2 on ice (the former weakens the latter); — increasing, and increasingly warm, rain fall on ice; — «stuck» weather systems bringing more and more warm tropical air ever further toward the poles; — melting of sea ice shelf increasing mobility of glaciers; — sea water getting under parts of the ice sheets where the base is below sea level; — melt water lubricating the ice sheet base; — changes in ocean currents -LRB-?)

Hence when the Mak cycle leads to reduce energy in the North ice sheets form, this increases albedo which reduces overall energy being absorbed by the plant and we have an ices.

What G&T are missing is the linear effect of water vapour accelerating the ice albedo effect of change in size of the sea ice sheets.

For example, the ice age — interglacial cycles that we have been locked in for the past few million years seem to be triggered by subtle changes in the earth's orbit around the sun and in its axis of rotation (the Milankovitch cycles) that then cause ice sheets to slowly build up (or melt away)... which changes the albedo (reflectance) of the earth amplifying this effect.

This was a relatively stable climate (for several thousand years, 20,000 years ago), and a period where we have reasonable estimates of the radiative forcing (albedo changes from ice sheets and vegetation changes, greenhouse gas concentrations (derived from ice cores) and an increase in the atmospheric dust load) and temperature changes.

As for irreversible, if an ice sheet starts flowing, or if an albedo change from sea ice gets locked in, I could imagine a climate change being essentially irreversible even if CO2 was brought back down, but it's just speculation, nothing more.

On the studies of sensitivity based on the last glacial maximum, what reduction in solar forcing is used based on the increased Albedo of the ice - sheets, snow and desert.

In LGM simulations land albedo changes are prescribed (at least in regards to ice sheets and altered topography due to sea level; there are feedback land albedo changes) so are a forcing, whereas sea ice is determined interactively by the model climate, so is a feedback in this frameworIn LGM simulations land albedo changes are prescribed (at least in regards to ice sheets and altered topography due to sea level; there are feedback land albedo changes) so are a forcing, whereas sea ice is determined interactively by the model climate, so is a feedback in this frameworin regards to ice sheets and altered topography due to sea level; there are feedback land albedo changes) so are a forcing, whereas sea ice is determined interactively by the model climate, so is a feedback in this frameworin this framework.

As I explained, you * can * get at climate sensitivity with the ice core record, but only by taking into account all the forcing (including, in particular, the ice sheet albedo).

(Orbital forcing doesn't have much of a global annual average forcing, and it's even concievable that the sensitivity to orbital forcing as measured in terms of global averages and the long - term response (temporal scale of ice sheet response) might be approaching infinity or even be negative (if more sunlight is directed onto an ice sheet, the global average albedo might increase, but the ice sheet would be more likely to decay, with a global average albedo feedback that causes warming).

So albedo change (owing to changes in orbital forcing, which is what melts the ice sheets) was comparable to, and probably larger than, the CO2 change.

Arctic sea ice extent reconstruction - Kinnard et al. 2011 Sea ice albedo feedback - NASA Polar jet stream - NC State University Greenland ice sheet surface melt - NASA Permafrost distribution in the Arctic - GRID - Arendal Atmospheric methane concentration - NOAA ESRL Russia plants flag at North Pole - Reuters

Based on evidence from Earth's history, we suggest here that the relevant form of climate sensitivity in the Anthropocene (e.g. from which to base future greenhouse gas (GHG) stabilization targets) is the Earth system sensitivity including fast feedbacks from changes in water vapour, natural aerosols, clouds and sea ice, slower surface albedo feedbacks from changes in continental ice sheets and vegetation, and climate — GHG feedbacks from changes in natural (land and ocean) carbon sinks.

These large CO2 deserts cover the northern ice sheets with dust, as is recorded in the ice core data, and the ice sheet albedo is lowered sufficiently so that the next insolation maxima can melt the ice sheets.

Human - caused global warming contributes to the summer Greenland warming (Figure 3), which causes snow to melt earlier, which causes decreased local albedo, which contributes to record Greeland ice sheet decline, which further decreases local albedo, which in turn contributes to the Arctic sea ice decline.

«The positive ice - albedo feedback acts to amplify the climate change as a consequence of the melting of sea ice and ice sheets in the Northern Hemisphere.

+ summer wildfire smoke in Canada (2004, 2005, 2009, 2014, 2017) and Russia (2006, 2011, 2012, 2013, 2014, 2016) + albedo reductions (reduction in brightness) over the Greenland Ice Sheet in 2010 and 2012 related to strong melt years.

A CO2 pulse in the atmosphere will take centuries to finally return to original levels, and that is completely ignoring any potential feedbacks from other parts of the system (ie temperatures raised for centuries could result in massve methane releases and loss of signficant low albedo ice sheets etc.) The experiments I am aware of that show improved plant growth in elevated CO2 levels require that all additional biological needs are amply provided for.

With the albedo - flip kicking in, the energy poured into killing off millennia - old MY ice will then go into the warming of the Arctic Ocean itself, with the result of longer and longer melt seasons each year & a corresponding ramp - up of ice loss from both the Greenland Ice Sheet and the West Antarctic Ice Sheice will then go into the warming of the Arctic Ocean itself, with the result of longer and longer melt seasons each year & a corresponding ramp - up of ice loss from both the Greenland Ice Sheet and the West Antarctic Ice Sheice loss from both the Greenland Ice Sheet and the West Antarctic Ice SheIce Sheet and the West Antarctic Ice SheIce Sheet.

http://earthobservatory.nasa.gov/IOTD/view.php?id=83672 http://www.nytimes.com/2014/05/13/science/earth/collapse-of-parts-of-west-antarctica-ice-sheet-has-begun-scientists-say.html It will add about 10 feet according to an interview with one of the scientists involved; but over a long time and fairly vague time frame, unless reinforcing processes (carbon release from melting permafrost, shallow ocean bottom warmingn in the form of methane from clathrates), a major reduction in earth's albedo from permafrost, net ice sheet, and total sea ice, continue to increasingly accelerate the process.

The melting of the ice sheets and the change in albedo and the change in the sea levels were all feedbacks as a result of the insolation change.

If these plumes of warm air operated in the same way during the last glaciation as they do know then they would make short work of ice sheets that were hanging around because of the albedo effect, this is possible because not all the northern hemisphere mid latitude land surface was covered with ice throughout the period of glaciation and might explain why glaciations terminate quickly

Comparisons of the impacts of shortwave and longwave radiative forcing appropriate over the ice sheets are not straightforward, but taking summer half - year insolation variations in shortwave (Figure 3), and assuming an albedo of 0.5 for melting ice, variations in summertime shortwave forcing exceed the direct CO2 radiative forcing by about a factor of five.

The remaining slow drift to lower GMT and pCO2 over glacial time, punctuated by higher - frequency variability and the dust − climate feedbacks, may reflect the consequences of the growth of continental ice sheets via albedo increases (also from vegetation changes) and increased CO2 dissolution in the ocean from cooling.

Albedo change due to LGM — Holocene vegetation change, much of which is inherent with ice sheet area change, and albedo change due to coastline movement are lumped together with ice sheet area change in calculating the surface albedo climate foAlbedo change due to LGM — Holocene vegetation change, much of which is inherent with ice sheet area change, and albedo change due to coastline movement are lumped together with ice sheet area change in calculating the surface albedo climate foalbedo change due to coastline movement are lumped together with ice sheet area change in calculating the surface albedo climate foalbedo climate forcing.

To avoid long response times in extreme climates, today's ice sheets are assigned surface properties of the tundra, thus allowing them to have a high albedo snow cover in cold climates but darker vegetation in warm climates.

These include intrinsic limitations in current observational capabilities (e.g., spatial and radiometric resolution of currently available spaceborne sensors) and limitations on how accurately surface energy balance models handle ice sheet albedo.

A fall of just a couple of degrees and you have increasing Ice sheets, Increasing Albedo, growing Glaciers, in short..