ROCKY REX'S SCIENCE BITES

Arctic permafrost – ground that has been frozen for many thousands of years – is now thawing because of global climate change. “The release of greenhouse gases resulting from thawing Arctic permafrost could have catastrophic global consequences,” said  Dr. Max Holmes, a Senior Scientist at the Woods Hole Research Center (WHRC). G reenhouse gas es and permafrost.   Graphic by John Garrett. Thawing permafrost releases greenhouse gases (carbon dioxide and methane) into the atmosphere, which accelerate climate change, which in turn cause more thawing of the permafrost.  This may be a fairly slow process, and there is a lot more research to be done in this area. Some scientists fear that this potentially unstoppable and self-reinforcing cycle could produce a dangerous "tipping point".

Oceania  is a region made up of thousands of  islands throughout the Central and South  Pacific Ocean.   It includes Australia, the smallest continent in terms of total land area. Many of the nations in Oceania are  Small Island Developing States (SIDS). Many scientists say that Oceania is more vulnerable than most parts of the Earth to climate change, because of its climate and geography.  The heavily coastal populations of the continent’s small islands are vulnerable to flooding and erosion  because of  sea level rise.   An international team of researchers  has produced this graph of ocean levels, for a period of time going back to around 500 BC.  Five of the Solomon Islands have been swallowed whole by rising sea levels between 1947 and 2014.  "It’s a perfect storm,” says  Simon Albert  of the University of Queensland. “There’s the background level of global sea-level rise, and then the add...

Heat can affect things without causing a temperature rise. Extra heat can be used in ‘ changing state ’ instead of raising temperature. A change of state could be … a  solid  melting to a  liquid .  Or a  liquid  evaporating to a  gas . So  heat is needed to change ice at zero degrees C to water at zero degrees C. And to change water into water vapour….. without raising the temperature. Scientists call the heat used to change state  latent heat. Also, there are natural variations in the global climate,  El Nino  events being the ones that affect world temperature the most. The opposite to 'El Nino' is 'La Nina', a cooling effect. If global temperatures are plotted on a graph in a way that shows these variations, it makes the overall warming trend very obvious. Every La Nina year since 1998 has been warmer than every El Nino year before 1995. As the Earth warms, each El Nino event 'rides' on a higher base-...

Deltas  often form when rivers reach the sea. The river can carry sand and mud when it is flowing fast. As the water enters the sea, it s lows down , and the sediment drops to make the delta. Many deltas are at risk from climate change.   This map shows the levels of risk. An estimated 80 percent of the world's megacities are located in fragile river deltas.   A megacity has a population of over 10 million people. Over 500 million people live on deltas. Why are deltas at risk? One reason  is  rising sea level , which wears away the delta from the front. Deltas are an example of the complex processes that happen along coastlines.

An  international research project  has found human activity has been causing global warming for almost two centuries,  according to a report in Phys.Org Australian National University researcher Associate Professor Nerilie Abram. Credit: Stuart Hay, ANU Lead researcher Associate Professor Nerilie Abram from The Australian National University (ANU) said that their study found that warming began during the early stages of the Industrial Revolution. Warming is first detectable in the Arctic and tropical oceans around the 1830s, much earlier than scientists had expected. CO2 information from ice cores shows that atmospheric CO2 levels began to rise from around 280 ppm as the 19th century began. Atmospheric CO 2  concentration over the last millennium, as reconstructed from ice core data obtained by  Etheridge  et al . (1998)  at  Law Dome , Antarctica.

When the last glacial period ended about 11,500 years ago, the Earth's modern climate began to develop.  The large continental ice sheets shrank, and sea level rose. Around 8,200 years ago, however, a major cooling event occurred.  The   8.2 ka event   was first discovered in the Greenland ice core  GISP2. Over two decades temperature cooled about 3.3°C in Greenland . Temperatures in Europe dropped by around 2 °C. The entire event lasted about 150 years. Then temperatures warmed, returning to their previous levels.  So what caused the 8.2 ka event? As the large ice sheets in Canada were melting, a large  meltwater lake  formed south of the Hudson Bay.   Geologists have named this  Lake Agassiz , after the  19th century scientist Louis Agassiz. It was dammed to the north by the  Laurentide  ice sheet . Slowly, the ice melted further, and the lake emptied into the sea in a...

Space is not very far away. Aircraft on long-haul flights travel at a height of about 10 km. The lowest layer of the atmosphere, the  Troposphere,  ends at about 15 km. The air in the layers above the troposphere is very thin indeed. Think of a place around 15 km (9 miles) from where you are. That's pretty much how near you are to space. All the waste gases people dump into the air are trapped in the thin layer of air around the Earth. Molecules  in the air include nitrogen and oxygen as well as water, carbon dioxide, ozone, and many other compounds in trace amounts, some created naturally, others the result of human activity. In addition to gases, the atmosphere contains extras such as smoke, dust, acid droplets, and pollen. Atmospheric concentrations   of some   greenhouse gases   over the last 2,000  years.