Today’s Image of the Week shows annual ice flow velocity mosaics at 1km resolution from 2005 to 2016 for the Antarctic ice sheet. These mosaics, along with similar data for Greenland (see Fig.2), were published by Mouginot et al, (2017) last month as part of NASA’s MEaSUREs (Making Earth System Data Records for Use in Research Environments) program. How were these images constructed? The mosaics s ...[Read More]
Image of the Week — Hidden lakes in East Antarctica !
Underwater picture of englacial lake 4m
below the surface [Credit: S.
Lhermitte].
Who would have guessed that such a beautiful picture could get you interviewed for the national news?! Certainly not me! And yet, the photo of this englacial lake (a lake trapped within the ice in Antarctica), or rather science behind it, managed to capture the media attention and brought me, one of the happy co-author of this study, on the Belgian television… But what do we see on the pic ...[Read More]
Katabatic winds – A load of hot (or cold) air?
Figure 1: A schematic of the potential wind flow and interplay of local effects on Tsanteleina Glacier in the Italian Alps. The diagram represents wind modelling, measured data and observations from the field. (1) The interactions of down-glacier katabatic winds (blue) and up-valley winds/local heat sources (red); (2) the potential heat emitted from the warm valley surroundings (pink) and; (3) localised surface depressions representing glacier 'cold spots' during calm, high pressure conditions. Arrows correspond to synoptic westerlies (purple), southerly airflow (orange), katabatic winds (blue) and valley winds (red) [Credit: T Shaw, unpublished] - Click here for a larger version.
It might seem obvious that a warming world will lead to a reduction in glacial ice cover, but predicting the response of glaciers to climatic change is no simple task (even within the short term). One way to approach this problem is to come up with relationships which describe how glaciers interact with the world around them, for example, how the ice interacts with the air above it. Our post today ...[Read More]
Image of the Week – For each tonne of CO2 emitted, Arctic sea ice shrinks by 3m² in summer
Mean area of Arctic September sea ice lost by CO2 emissions of each citizen for each country of the world in 2013. These results are based on the observed trend of 3 m² sea-ice area loss per tonne of CO2 emitted [Credit: adapted from Notz and Stroeve (2016), Fig.S1]
Declining sea ice in the Arctic is definitely one of the most iconic consequences of climate change. In a study recently published in Science, Dirk Notz and Julienne Stroeve find a linear relationship between carbon dioxide (CO2) emissions and loss of Arctic sea-ice area in summer. Our image of this week is based on these results and shows the area of September Arctic sea ice lost per inhabitant d ...[Read More]
Black Carbon: the dark side of warming in the Arctic
Greenland in summer: ice is covered by dark particles -- Black Carbon -- which amplify melting.
[Credit : NASA ICE distributed via flickr]
When it comes to global warming, greenhouse gases – and more specifically CO2 – are the most often pointed out. Fewer people know however that tiny atmospheric particles called ‘black carbon’ also contribute to the current warming. This post presents a paper my colleague and I recently published in nature communications. Our study sheds more light into the chemical make-up of black car ...[Read More]
Image of the Week – Satellite Measurements of Arctic Sea Ice
The map above shows the region around Fram Strait that separates Greenland and Svalbard (Spreen et al., 2009) . The colours show the amount (volume flux) of sea ice that was moving from the Artic Basin and south in October/November 2006 as measured by satellites. The arrows show the direction of sea ice.
Sea ice is an important part of the Earth’s climate system. When sea ice forms, it releases heat and salt. When sea ice melts, it takes up heat and adds freshwater to the salty ocean water. It is also important for the exchange of energy between the atmosphere and the ocean surface, and for the ocean currents that transport warm and cold water from the equator to the poles and back. The main route ...[Read More]
Image of the week – The winds of summer (and surface fluxes of winter)
Representation of the (a) summer and (b) winter oceanic circulation within the Adélie region, East Antarctica.
MGT = Mertz Glacier Tongue (red dot on the Antarctica map); other acronyms indicate different water masses: Antarctic Surface Waters (AASW), Modified Circumpolar Deep Water (MCDW*), Dense Shelf Water (DSW) and Antarctic Bottom Water (AABW) explained below. [Credit: reprinted with permission from Snow et al. (2016, figure 4) ]. Click here here to enlarge the image.
Antarctica is separated from the deep Southern Ocean by a shallow continental shelf. Waters are exchanged between the deep ocean and the shallow shelf, forming the Antarctic cross-shelf circulation: Very dense waters leave the shelf as Antarctic Bottom Water (AABW) that will then flow at the bottom of all oceans. Meanwhile, relatively warm water from the Southern Ocean, Modified Circumpolar Deep W ...[Read More]
Image of the Week – Mushrooms at zero degrees = hair ice?!
Hair ice in a forest near Moosseedorf, Switzerland (Credit: Christian Mätzler)
When you go down to the woods today you’re in for a big surprise….. hair ice! Did you know that there is a type of ice called hair ice? It is shaped like fine, silky hairs and looks like white candy floss. It grows on the rotten branches of broad-leaf trees during humid winter nights when the air temperature drops slightly below 0°C. A 100-year-old theory states that hair ice a ...[Read More]
Image of the Week – Storing water in Antarctica to delay sea-level rise
Difference in ice thickness from the initial equilibrium state after 100 years of ice addition (upper panels) and 1000 years after the end of the forcing (lower panels). Two scenarios are shown, 200 km (left panels) and 800 km (right panels) from the coastline, both corresponding to a sea-level mitigation of 10 mm per year (credit: Frieler et al., 2016, fig 3) .
Sea level rise Sea-level rise is one of the main impacts of the current global warming and its rate has dramatically increased in the last decades (the current rate is about 3 mm per year). Even if greenhouse gas emissions were stopped today, sea level would continue to rise due to the slow Earth climate system response (IPCC, 2013, chap. 13). It is therefore a considerable threat for popul ...[Read More]