Question

what positive changes have occurred on earth after the speaker visit​

Answer 1

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From the oceans to continental heartlands, human activities have altered the physical characteristics of Earth's surface. With Earth's population projected to peak at 8 to 12 billion people by 2050 and the additional stress of climate change, it is more important than ever to understand how and where these changes are happening. Innovation in the geographical sciences has the potential to advance knowledge of place-based environmental change, sustainability, and the impacts of a rapidly changing economy and society.

Answer 2

Answer:

Accelerated human modification of the landscape and human-driven climate changes are fundamentally altering Earth’s surface processes and creating ecological challenges that scientists and policy makers are struggling to address. The environmental impacts of human activity are expected to increase as the climate continues to warm and as the world becomes progressively more populated, industrialized, and urbanized. Scientific research has generally succeeded in documenting the magnitude of these biophysical changes, including habitat loss and fragmentation, soil erosion, biodiversity loss, and water depletion and degradation. Yet the exact processes leading to these changes are still not adequately understood and quantified, and we still lack the best methods and techniques for detecting, measuring, and analyzing global change.

Soil erosion provides a prime example to understand what is at stake. Although a natural process, soil erosion has greatly accelerated globally due to cultivation, deforestation, and a host of other land-use practices (Montgomery, 2007a,b; Figure 1.1). Increased soil erosion generates sediment supply that often exceeds the transport capacity of stream systems, leading to vast sediment storage on channel beds, on hillslopes, and in floodplains. This historical sedimentation has already had significant impacts on channel processes, aquatic systems, and fisheries (Waters, 1995; NRC, 2004). Moreover, these legacy sediments represent a future risk because they can be remobilized and introduced into aquatic systems even following landscape amelioration (Walter and Merrits, 2008).

Anticipated climate change will heighten the human impact on the physical environment in many places. Predicting the magnitude and timing of these future impacts remains uncertain, but measurable changes have already occurred climatically (Elsner et al., 2008) and hydrologically over the past few decades, with earlier ice-out dates, reduced magnitudes of spring runoff and summer low flows, and changes in the timing of peak streamflows (Hodgkins et al., 2002, 2003; Huntington et al., 2003, 2004). Future climate change will likely bring greater hydrological and ecological shifts nationally and globally, with potentially profound impacts on water availability

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