ROCKY REX'S SCIENCE BITES

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

The highly respected  Berkeley Earth  project has reported that  2016 was the warmest year in the modern record. This chart shows the  annual average global temperatures  up to 2015, from NASA's  Goddard Institute for Space Studies ( GISS ) One thing to note ….. every  La Nina   ‘year’ since 1998 was warmer than every   El Nino  ‘year’ before 1995.   It's useful to look at average global temperatures by comparing decades. This chart comes from the  World Meteorological Organisation. The high figures in the 1930s and 1940s were produced partly because there were strong El Ninos over a period from about 1939 to 1942. Since the mid 20th century global temperatures have risen, decade by decade. New research  published June 2015 confirms this trend: Over a longer term, it's obvious that the current situation is unusual. Source: Sir John Houghton A temperature rise of  2 degrees  C  above pre-industrial temperature has been agreed as a threshol

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 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.

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

In places which are not as frozen as they were, amazing discoveries have been made. In 1991 two hikers in the Alps found a body. They were shocked, and reported the find. It was even more extraordinary when the investigation found that the body was thousands of years old. The clothing, weapons and other items found with the body give a glimpse into life when metal was first being used. Tests later confirmed the iceman dates back to 3,300 BC. He probably died from a blow to the back of the head.  His body was so well-preserved that scientists were able to determine that his last meal was red deer, herb bread, wheat bran, roots and fruit. He lived at a time, over 5,000 years ago, when the Earth was starting to cool. So when he died high in the mountains, his body became covered with snow. Modern warming (shown by the red part of the graph) made it possible to find him.

What do scientists mean by the " Greenhouse Effect "? 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. An extreme case has happened on Venus. Concentrated  'greenhouse gases'  on Venus have caused the surface temperature to rise to 735  Kelvin  (462 degrees C; around 900 degrees F) Carbon dioxide levels in the atmosphere have risen quickly  since people began burning large quantities of fossil fuels. There was carbon dioxide in the air before that, at around 270 parts per million. Without any carbon dioxide, the Earth would be ver