ROCKY REX'S SCIENCE BITES

An international team of researchers  has produced this graph of ocean levels, for a period of time going back to around 500 BC.  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.   Fiji’s  shoreline has been receding about 15 centimetres per year over the last 90 years. Samoa  has lost about half a metre per year during that same time span.  The global sea level graph is from this paper:  "Temperature-driven global se...

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.

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.

The northern hemisphere  winter  , December 2014 to February 2015, was the warmest in the records,  according to NASA. The average temperature, taken for northern land and ocean surfaces, was  0.79°C above the 20 th   century average.  This was the highest for December, January and February in the 1880–2015 record, passing the previous record of 2007 by 0.03°C. It is interesting to note that there were some 'cold spots'. Eastern North America was colder than average, and there is an obvious 'blue blob' in the North Atlantic. In 2015,  Boston ’s month of snow was a  1-in-26,315 year occurrence.

New research  has shown amazing connections between ancient underwater  volcanic eruptions  and the Ice Age. Volcanoes on the ocean floors flare up in  regular cycles , ranging from two weeks to 100,000 years.  The study  suggests that these seafloor volcanoes might have helped trigger  natural climate swings  in the past. The idea is that the volcanic cycles might be tied to cycles in Earth’s orbit – the  Milankovitch cycles  – and to changing sea levels. The volcanoes give off carbon dioxide (CO 2 ), and they change how much CO 2  is in the air. The graph shows that highest value of CO 2  produced in this way is around 280 parts per million of air. There is no direct link to current climate change in this discovery, as the air now contains around 400 parts per million of carbon dioxide. The extra carbon dioxide in the air seen in recent times has been produced by burning fossil fuels.

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 very short period of time. The r...

Diagram: NASA 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. Stratosphere The stratosphere starts just above the troposphere and extends to 50 kilometres (...

Between about 20,000 and 5,000 years ago, Earth slowly changed from the frigid conditions of an  Ice Age , to the world on which our civilization has developed. As the  ice sheets  melted, colossal volumes of  water  flowed back into the oceans. The  pressures  acting on the Earth's crust changed as a result.  The  weight of ice  on the continents was reduced, and the rising seas put  extra water pressure  on the seafloors. In response, the  crust  moved up and bent, creating extra volcanic activity, increased seismic shocks and giant landslides. So if we continue to allow greenhouse gas emissions to rise unchecked, causing serious warming, will our planet's crust react once again? In Alaska, climate change has pushed temperatures up by more than 3 degrees Celsius in the last half century, and  glaciers  are melting at a staggering rate, some losing up to 1 kilometre in thickness in the last 10...

Marlin  can hunt in water a half mile down, and sailfish often dive deep too. In more and more places around the world, ocean predators are sticking near the surface. Why? Warming temperatures are  sucking oxygen out of waters  even far out at sea, making enormous stretches of deep ocean hostile to marine life. Vast stretches of the ocean interior  suddenly lost oxygen  during the transition out of the last  glacial stage , between 17,000 and 10,000 years ago.  This event was the most recent example of large-scale global warming.

This graph shows how  carbon dioxide  has increased and decreased over hundreds of thousands of years. The low readings match with times called ' glacial stages '. During glacial stages,  ice  covered large areas of the Earth. The peaks in the graph show times when carbon dioxide was high, matching times called ' interglacial stages '. The most recent glacial stage occurred between about 115,000 and 11,500 years ago.   The  last interglacial period  occurred before it, from around 130,000 to 115,000 years ago. It's official international name is the  Eemian,  but it has other names in specific places. Climate information from that time is particularly useful. During that time,  temperatures  on earth were higher at the poles than they are now.  The  sea level  was between five and nine metres higher than current levels, because of the melting of ice in  Greenland  and  A...

July 2015 was the warmest month in the modern temperature record. The average temperature for July 2015 across global land and ocean surfaces was 1.46°F (0.81°C) above the 20 th  century average, according to the United States National Oceanic and Atmospheric Administration. They say: "As July is climatologically the warmest month for the year, this was also the all-time highest monthly temperature in the 1880–2015 record, at 16.61°C, surpassing the previous record set in 1998 by 0.08°C." Previous months in 2015  have also shown a warming trend is continuing, following the record-breaking  year 2014.

The climate can react to sudden shocks. The weather in  1816  was very strange.  Spring arrived, but then everything seemed to turn backward, as cold temperatures returned.  The sky seemed permanently overcast.  T he lack of sunlight became so  severe that farmers lost their crops. Food shortages were reported in Ireland, France, England, and the United States. 1816 became known as "The Year without a Summer"  or "18-hundred-and-frozen-to-death". It was over 100 years before anyone understood the reason for this weather disaster. The eruption of an enormous volcano on a remote island in the Indian Ocean a year earlier had thrown enormous amounts of volcanic ash into the upper atmosphere. The dust from  Mount Tambora , which had erupted in early April 1815, had shrouded the globe.  With sunlight blocked, 1816 did not have a normal summer. In Switzerland, the dismal...

Oil is a  fossil fuel . It was formed from chemicals from ancient living things. To make the chemicals in oil, the  temperatures  and  pressures  needed to be just right. The oil (and gas) will only stay in the reservoir if there are suitable structures  in the rocks: The carbon compounds from the plants and animals have been trapped for hundreds of millions of years. They have been burned to make carbon dioxide in a very short time. The amount of carbon dioxide in the air has changed very quickly. Diagram of how oil is made Source:  Library and Archives Canada © Library and Archives Canada nlc-11167

Yes, global warming has happened before. Scott L. Wing is a research scientist and curator at the Smithsonian’s Museum of Natural History. One of Scott's major research interests is the PETM. "The Paleocene-Eocene Thermal Maximum (PETM) was an abrupt global warming event. It occurred at the beginning of the Eocene Epoch , about 55.8 million years ago.  At the start of the event something like 5-10,000 gigatons of carbon were released into the ocean and atmosphere in less than 10,000 years.  As a result of the carbon release, temperatures rose 5-9˚C globally.  The PETM is widely recognized by scientists as the best geologic analogy for the human-induced global warming that is happening now." Badlands of the PETM in the southeastern Bighorn Basin in Wyoming, USA. However, the current production of greenhouse gases by humans is far faster than the events that caused the PETM. It took around 150,000 years for ecosystems to recover from this ev...

T he  Gulf Stream  transports vast amounts of heat north, from the equator to the pole, passing off the East Coast of the U.S. and into the North Atlantic. The  Northern Hemisphere winter of 2014-15  was the warmest on record globally, according to the National Oceanic and Atmospheric Administration.  But one area of the  North Atlantic   was the coldest on record... shown in blue on this map. This cold pool may be  an indicator of a dramatic slowdown in the  Gulf Stream. A slowdown like this in the current has not happened for a very long time, perhaps as long as 1,000 years.  It is possibly related to the melting of the  Greenland  ice sheet.  The  freshwater  from the ice sheet  is  lighter  than heavier, salty water that usually occupies that area.  It tends to sit on top of the water,  interfering with the sinking of dense, cold and salt-rich water. The Gulf Stream transpo...

Climate change will affect people in many ways. Sea levels are rising more than twice as fast as the global average in the  Sunderbans. The Sundarbans are  a low-lying delta region made up of 200 small islands in the Bay of Bengal. Around 13 million impoverished Indians and Bangladeshis live in t he Sundarbans   . Scientists predict much of the region could be underwater in 15 to 25 years, forcing the largest ever human migration in history. A  2013 study by the Zoological Society of London  found the Sundarbans coastline retreating at about 200 metres a year.

El Niño  is an  oscillation of the ocean-atmosphere system in the tropical Pacific , and has important consequences for weather around the world. El Niño  happens every three to seven years. “El Niño” is Spanish for “The Christ Child”. Peruvian fishermen named the event many years ago. They noticed that every few years around Christmas, virtually no fish could be found in the unusually warm waters.  El Niño is marked by  unusually warm ocean temperatures  in the Equatorial Pacific. The opposite conditions are called  La Nina , characterized by  unusually cold ocean temperatures  in the Equatorial Pacific.  El Nino clearly affects global temperatures. One piece of evidence that world temperatures are rising is that every  La Nina  ‘year’ since 1998 was warmer than every  El Nino  ‘year’ before 1995:   As the Earth warms, each El Nino 'rides' on a higher base-line global temperature:...

Lots of people discuss ' climate change '. Some people confuse 'climate' with 'weather'. If 'climate' and 'weather' are the same, why would there be two words? Other people say "We call climate change 'winter' and 'summer'...."   What does the word ' climate ' mean? It normally means  the average of conditions over 30 years . Climate  normally means 'an average over 3 conventional decades'. A  conventional decade  is, for example, 2001-2010, or 1961-1970. So ..... 3 full, conventional decades......such as 1981 to 2010. For example .... rainfall in Ireland. And another example -  ' A verage temperature 1951-1980' The definition of 'climate' goes back at least 100 years. So if we are discussing  climate change , that is what 'climate' means. But in recent times, there has been a lot of variation in global temperatures. So it can be ...