Question

During the 1980's and 1990's global marine NPP decreased by 6%. What was the driver(s) behind this decline?

Question 9 options:

Increasing temperatures

Atmospheric iron deposition

Sea level rise

Increasing temperatures and atmospheric iron deposition

Increasing temperatures, atmospheric iron deposition, and sea level rise

Answer 1

Increasing temperatures were the driver behind the decline in global marine NPP during the 1980's and 1990's.

Step-by-step explanation:

The driver behind the decline in global marine net primary productivity (NPP) during the 1980's and 1990's was increasing temperatures.

Warmer temperatures can negatively impact marine ecosystems by affecting nutrient availability, altering ocean currents, and reducing the growth rates of phytoplankton, which are the primary producers in marine food chains. This decline in NPP can have cascading effects on marine organisms and entire ecosystems.

While atmospheric iron deposition and sea level rise can also have impacts on marine NPP, the given information specifically states that the decline in NPP was caused by increasing temperatures.

Answer 2

The 6% decline in global marine NPP during the 1980s and 1990s was primarily driven by increasing temperatures resulting from higher greenhouse gas emissions which lead to ocean acidification and ecosystem disruption. So the correct answer is Option 1.

Step-by-step explanation:

The decline in global marine NPP (Net Primary Production) during the 1980s and 1990s by 6% can be primarily attributed to increasing temperatures. This rise in temperature is associated with increased greenhouse gas emissions since the Industrial Revolution, which has led to higher concentrations of carbon dioxide in the atmosphere. The rising CO₂ levels result in ocean acidification and thermal stress on marine organisms, disrupting the balance of marine ecosystems and decreasing NPP. Additionally, atmospheric iron deposition can influence marine productivity in iron-limited regions, but it is generally not considered a significant driver of NPP decline in the context of your question.

It is important to note that while sea level rise is a consequence of climate change, it is not directly linked to the decline in NPP. The primary cause that underlies the reduction in marine NPP is the global rise in air and ocean temperatures due to increased greenhouse gas emissions.