Some meteorites contain organic compounds which may be precursors to today's living cells,<span> provides evidence to support this idea.</span>
Climate change will affect most aspects of our lives in Canada. Our economic, social and general well-being are all linked, both directly and indirectly, to climate. For example, climate influences the crops we grow, the productivity of our forests, the spread of disease, the availability of water, the health of ecosystems and the stability of our infrastructure. Changing climate brings many new challenges and, with them, the need to re-examine long-standing practices and assumptions.
Our climate is characterized by high variability, on both seasonal and annual scales. Although our economy, health and infrastructure are generally well adapted to current climate conditions, our vulnerability to climate is clearly evidenced by the impacts resulting from extreme weather and climate events. Losses from recent individual weather-related disasters in Canada are often in the hundreds of millions of dollars. Consider, for example, costs associated with the 2003 summer wildfires in British Columbia and Alberta ($400 million; Public Safety Canada, 2005), the 1991 and 1996 hailstorms in Calgary ($884 million and $305 million, respectively; Public Safety Canada, 2005), the 1997 Red River Flood ($817 million; Public Safety Canada, 2005) and 2003 Hurricane Juan in Halifax ($200 million). Multibillion dollar disasters also occur, including the 1998 ice storm in eastern Canada ($5.4 billion) and the Saguenay flood in 1996 ($1.7 billion; Public Safety Canada, 2005). The 2001 -2002 droughts, which were national in scale, resulted in a $5.8 billion reduction in gross domestic product (Wheaton et al., 2005). Extreme weather and climate events impact the health and well-being of Canadians beyond monetary costs, as they frequently involve displacement, injuries and loss of life. For example, the 1998 ice storm led to the greatest number of injuries (945) and 17 800 evacuations (Public Safety Canada, 2005). Unusually heavy rainfall following a period of drought was a contributing factor to the E. coli outbreak in Walkerton, Ontario in 2000 that resulted in seven deaths and thousands of people becoming ill (O 'Connor, 2002).
Increases in temperature and changes in precipitation have been observed across most of Canada over the past century. During the past 50 years (1948-2006; the period for which data are available for both northern and southern Canada), average national temperature has increased 1.3 °C (see Chapter 2; Environment Canada, 2006). This is more than double the increase in mean global surface temperature during the same time interval. Canada is projected to continue to experience greater rates of warming than most other regions of the world throughout the present century (see also Chapter 2; Environment Canada, 2006). The magnitude of changes in climate will vary across the country, with northern regions and the south-central Prairies warming the most (Figure 2). Average annual precipitation is also projected to rise, although increases in evaporation and transpiration by plants in some regions are expected to more than offset increases in annual precipitation, resulting in increased aridity. More frequent heavy precipitation events, less precipitation during the growing season and more precipitation during the winter are also projected for Canada
The answer would be C. Germany has recently changed the legal retirement age to 67.
Answer
Accelerates algal growth and reduces oxygen.
Explanation eutrophication is the nutrient induced increase in phytoplankton productivity.
Answer:
During the Silurian , the Earth witnessed many changes in the way in which landmasses were distributed around the globe. Although there were no major volcanic events, a deglaciation and rise in sea levels occurring at that time produced varying periods of continent coverage and exposure. The variation of ocean levels occurred alongside the process of continental fragmentation and grouping that occurred from the Cambrian to the present.
At that time, the continents were distributed very differently than they are today. The Silurian world consisted of a vast north polar ocean and a south polar supercontinent (Gondwana) with a ring of approximately six continents. By the Silurian period, a large portion of the Rodinian landmass had become fragmented, and those fragments migrated toward the equatorial region. Most of these fragments were eventually assembled by a series of plate collisions into the super-continents of Laurussia and Laurasia. The modern Philippine islands were most likely inside the Arctic Circle, while Australia and Scandinavia resided in the tropics; South America and Africa were probably over the South Pole.
There was no major volcanic activity during the Silurian; however, the period is marked by major orogenic (mountain-building) events in eastern North America and in northwestern Europe, resulting in the formation of the mountain chains there. This was called the Caledonian Orogeny. In other areas, large igneous rock formations of the Middle Silurian arose, such as those in Central Europe, as well as light sedimentation throughout the Baltic region. While not characterized by dramatic tectonic activity, the Silurian world experienced gradual continental changes that would be the basis for greater global consequences in the future, such as those that created terrestrial ecosystems.
The Silurian oceans are also of particular interest for activity between the regions known as Laurentia, Baltica and Avalonia. The ocean basins between these areas substantially closed together, continuing a geologic trend that had begun much earlier. The new marine habitats produced by these profound changes in the Silurian seas provided the framework for significant biological events in the evolution of life. Coral reefs, for example, made their first appearances in the fossil record during this time.
The Silurian period was a time when the earth underwent considerable changes that had important repercussions for the environment and the life within it. The Silurian witnessed a relative stabilization of the world's general climate, ending the previous pattern of erratic climatic fluctuations. One significant feature of these changes was the melting of large glacial formations. This contributed to a substantial and significant rise in the levels of the major seas, creating many new marine habitats.
The Silurian period's condition of low continental elevations with a high global stand in sea level can be strongly distinguished from the present-day environment. This is a result of the flood of 65% of the shallow seas in North America during the Llandovery and Wenlock times. The shallow seas ranged from tropical to subtropical in climate. Commonly present in the shallow seas were coral mound reefs with associated carbonate sediments. Due to reduced circulation during the Ludlow and Pridoli times, the process of deposition of evaporites (salts) was set in motion. Some of these deposits are still found in northern Europe, Siberia, South China and Australia.
Explanation:
