ROCKY REX'S SCIENCE BITES

Coal, oil and natural gas are  fossil fuels . When they are burned, they  change the Earth's atmosphere. How is that possible?       C oal  is a good example. Coal was formed  hundreds of millions of years ago . Geologists say that a three-metre (10-foot) coal seam took between  12,000 and 60,000 years  to form . Ancient trees and other plants lived, died and were fossilised. All those plants took  carbon dioxide  out of the atmosphere.  Some larger coal seams are, for example, 10 metres thick. They took around  40,000 years to form,  but have been mined and burned in a little over  100 years. The fastest rise of CO 2  in the air seen in   the ice core record (800,000 years)  is  20 ppm in 1000 years. The CO 2  level in the atmosphere is now rising at around  20 ppm per decade . The  carbon  joins up with  oxygen  when it burns. Each  carbon atom  joins with two  oxygen atoms  to make a  carbon dioxide molecule .  As a result,  oxygen concentrati

Carbon sinks  are natural systems that suck up and store  carbon dioxide  from the atmosphere. The main natural carbon sinks are  plants, the ocean and  soil.   Plants  grab carbon dioxide from the atmosphere to use in  photosynthesis ; some of this carbon is transferred to soil as plants die and decompose.  The  oceans  are a major carbon storage system for carbon dioxide.  Marine life also takes up the gas for photosynthesis, while some carbon dioxide simply dissolves in the seawater. 35 billion tonnes  of CO2 are produced each year by human activities. Currently, natural processes are absorbing about half of that. The figure of 33.4 billion metric tonnes of carbon dioxide is for 2010.   The remaining carbon dioxide is building up in the atmosphere.

Healthy  coral  can be very colourful. Some coral reefs have started to look rather different. This is called ' coral bleaching '. To understand this, we need to start by looking at corals. Corals are animals that make a framework around them  that looks like rock. Coral animals ( polyps ) have tiny  plants -  algae  - living in their tissues. The algae provide food to the corals, which they produce by  photosynthesis . Reef-building corals only live in a limited temperature range. Like porridge, they should be 'not too hot and not too cold'. Coral reefs  are concentrated in a band around the equator, between 30 ° N and 30 ° S latitude. Algae in corals need light Corals grow in warm, clear, shallow waters that receive plenty of light. Most corals grow in the warmest water they can stand (about 85° F or 29° C).  This means that slight increases in ocean temperature can harm corals. High sea temperature is the main reason for coral bleaching.

Many people think climate change always happens slowly, but that is not the case......rather than hundreds, or thousands, of years, sometimes it can happen in decades. "Abrupt climate change"  was discovered by accident by Russell Coope (1930-2011), over 50 years ago. More recently he said: "We are  messing with the trigger  that causes climate change....the outcome is likely to be ferocious." In the 1950s, Russell Coope was a young geologist. He was studying layers of sediment formed during the  "Ice Ages" , a time geologists call the  Quaternary . He spotted something unusual in a quarry in the English Midlands.   This is his own description of what he found ... "I happened, entirely by accident, to visit a Quaternary gravel pit in which were exposed the spectacular bones of mammoth, woolly rhinoceros and bison.  Looking at their sediment matrix I was amazed to find enormous numbers of equally spectacular, if somewhat smaller, insect remai

It is often claimed that the  Sun  is causing global climate change. The Sun  is  the source of the heat on the Earth, but  it has not suddenly become more active recently. The Sun may be going into a phase of lower activity - but that will not reverse global warming. When the Sun's energy arrives at the Earth, it travels through the air. Some is reflected back to space, but some hits the Earth and warms it. The warm Earth gives off  infrared radiation  with various wavelengths.   Some of those waves can pass back out of the air to space, but some are absorbed by certain gases in the air. The gases then re-emit the energy into the air. If there are more of those gases, less heat escapes into space, so the Earth warms. In the graph below, from the  Stanford Solar Center , carbon dioxide data comes from the Law Dome ice core in Antarctica, and from the observatory on Mauna Loa in Hawaii. The Earth has warmed, even though there has been no

Heavy rainstorms caused devastating flooding across a 12-county region of West Virginia in late June 2016. Events like this are almost certainly made more frequent, and more intense, by global warming.  Climate scientists from around the USA  said  that the overwhelming scientific evidence shows that the warming of the planet’s atmosphere is increasing the occurrence of, and the seriousness of, heavy rains. Warmer air holds more water, leading to stronger and more frequent heavy precipitation events.  This is confirmed by research done by  a team of scientists of the Potsdam Institute for Climate Impact Research. They find the worldwide increase to be consistent with rising global temperatures, caused by greenhouse-gas emissions from burning fossil fuels.  Short-term torrential rains can lead to high-impact floodings.

Some people claim the current climate change has " natural causes ". They talk about the changes during the  'Ice Age' , thinking the current events must be natural as well. Scientists say that is not the case. The current situation is different. The things that caused the changes in the Ice Age are not exactly the same this time. The graph below shows that carbon dioxide in the air has increased and decreased over hundreds of  thousands of years. The  recent increase in carbon dioxide is much bigger and faster  than the natural changes. The low readings match with times called  'glacial stages'. During glacial stages, ice covered large areas of the Earth. The most recent glacial stage occurred between 115,000 and 11,500 years ago.  The peaks in the graph show times when carbon dioxide was high. Those times are called  'interglacial stages' .   Glacial and interglacial stages are linked to regular patterns in the movements of the Eart

Sea level is rising , and there are several reasons connected to  global warming . An international team of researchers  has produced this graph of ocean levels, for a period of time going back to around 500 BC.  Extra water enters the sea when  ice melts  from Antarctica, Greenland and other glaciers and ice caps. Recent research suggests that  the glaciers of Alaska alone now contribute 75 gigatonnes per year. S eawater also expands  as it gets warmer, just like the liquid in a thermometer expanding as temperatures rise.  This is called 'thermal expansion.' Investigating sea level rise involves scientists using many different methods, including satellites which map the surface of the sea. It is also important to look carefully at older records from tidal gauges all over the world. Global sea level rise from the 20th century to the last two decades has speeded up even more than scientists previously thought, according to  a new Harvard study. NASA have report

Some key events in the discovery of climate change 1800-1870  Level of carbon dioxide gas (CO 2 ) in the atmosphere, as later measured in  ancient ice , was about 290 ppm (parts per million). Global temperature for 1850-1870 was about 13.6°C. 1824 Jean-Baptiste Joseph F ourier  calculated that the Earth would be far colder if it lacked an atmosphere.  1856 Eunice Foote   describes filling glass jars with water vapour, carbon dioxide and air, and comparing how much they heated up in the sun. “The highest effect of the sun’s rays I have found to be in carbonic acid gas,”    “The receiver containing the gas became itself much heated – very sensibly more so than the other – and on being removed, it was many times as long in cooling.” 1859 John Tyndall  discovered that some gases block infra-red radiation.  He suggested that  changes in the concentration of the gases  could bring  climate change . 1896  Arrhenius  published the first calculation of glob

Average global temperature  is now higher than it has been for a long time. Graph by Klaus Bitterman. Green dots show the 30-year average of the  PAGES 2k reconstruction.   The red curve shows the global mean temperature, based on  HadCRUT4  data from 1850 onwards.  In blue is the original "hockey stick" from  a  paper by Mann, Bradley and Hughes (1999)  with its uncertainty range (light blue).  The green dots are calculated using data from many places around the world, using information from a range of  temperature proxies , such as documents, ice, lakes, pollen, tree rings, corals, seabeds and  speleothems. 78 researchers from 24 countries, together with many other colleagues, worked for seven years in the "PAGES 2k" Project  on this climate reconstruction.  Their study  is based on 511 climate archives from around the world. PAGES is the  Past Global Changes  programme launched in 1991. 

Ice cores   are cylinders of ice, drilled from an ice sheet or a glacier.  They are usually 10 centimetres in diameter, and can be taken from deep in the ice. Ice cores provide  trapped samples of ancient air . Dr Emilie Capron of the   British Antarctic Survey   said - "Air bubbles trapped in ice are like little time capsules that record the past atmospheric composition.  "So we measure loads of different gases, and essentially we can measure greenhouse gases such as carbon dioxide and methane." Most ice core records come from  Antarctica  and  Greenland. Law Dome   is a location in Antarctica. The evidence in Law Dome ice cores shows that since the 18th century, when the Industrial Revolution began, the level of carbon dioxide has risen. It has changed from around 280 parts per million to 315 ppm when Keeling began his records in 1958. Now it has reached around 400 ppm, a rise of 85 ppm in just 56 years.   The longest ice cores are f

Glaciers   are melting quickly in many places. Grinnel Glacier - at the top, 1940, compared with the lower image from 2006.  Repeat photography   reveals this process. Mount Lyell is in Yosemite National Park, California. New research shows that  glacier retreat is a global phenomenon  and is being caused by climate change: ....in many places, the centennial-scale retreat of the local glaciers does indeed constitute categorical evidence of climate change. In 2014 ,  Exit Glacier  in Alaska melted and retreated 57 metres toward the Harding ice field, which itself has lost 10 per cent of its mass since 1950. Easton Glacier in 1990, 2003 and 2015 from same location.