ROCKY REX'S SCIENCE BITES

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 ba...

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. 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 estimated 80 percent of the wo...

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 ...

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...

The constellation of  Orion  dominates the southern sky during winter in the Northern Hemisphere. The brightest stars of Orion have wonderful names. The Red Giant star  Betelgeuse  marks one shoulder, the other shoulder is marked by  Bellatrix . The three Belt Stars (left to right) are  Alnitak ,  Alnilam  and  Mintaka. The knees are marked by  Saiph  and the very bright  Rigel . Like many star names, they are of Arabic origin . The stars of Orion act as signposts to other stars seen at the same time of year. Orion's stars are good examples of some of the wide variety of types of stars.   The Sun is really rather small compared to many stars

Hurricanes, cyclones, and typhoons are all the same weather phenomenon. We use those different names for these  tropical storms  in different places.  In the Atlantic and North-East Pacific, the term  “hurricane”  is used. Image of Hurricane Patricia tweeted by  astronaut Scott Kelly . In the North-West Pacific a tropical storm is called a  “typhoon” , and  “cyclones”  occur in the South Pacific and Indian Ocean. Three strong tropical storms  (Kilo ,  Ignacio , and  Jimen a) ,  formed in the Pacific in 2015.  On Sunday 30th August, all of them were a category 4.  This was the first time the north-eastern Pacific had seen three category 4 hurricanes at the same time. Multiple cyclones in the Pacific Ocean in 2015 Tropical storms  can’t form outside the tropics - water temperatures are too cold. Sea surface  temperature  must be at least 27 ° C , and this temperature is actually requi...

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. New research  shows that this problem is getting worse. 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. There are other examples in the geological record, including the  Zechstein Sea.

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...

Summer in the south, winter in the north. Seasons are caused by the tilt in the Earth's axis. Winter Solstice is the time of the longest night and shortest day. Many ancient monuments are lined up with the solstice, which suggests it was an important moment of the year for many cultures. One is  Maeshowe  on Orkney. Others include  Stonehenge  and  Newgrange . Winter solstice sunset at Stonehenge in the mid-1980s. Image via Wikimedia Commons. Archaeologists have found evidence that p rehistoric people brought animals to  Stonehenge  from as far as north-east Scotland, to take part in midwinter feasts and ceremonies. One of the key researchers who has made a special study of Stonehenge in recent years is  Professor Mike Parker Pearson. He has written a number of academic papers and books on these recent discoveries.

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 Switzer...